[Guide] RCA Voyager RCT6873W42 Unlock Boot loader and root

[mrmazak]

Root has been achieved for rca tablet, With the intel atom chip


Basic steps are Just like many android devices.

1. Unlock boot loader
2. Flash modified stock recovery
3. Test boot a permissive boot.img
4. Flash permissive boot.img (if test boot was ok)
5. Boot into Custom recovery and flash superSu.

The modified recovery has adb active. This is needed to get back into bootloader mode if flashing goes wrong.
Because on the RCA tablet there is no button combination for bootloader boot mode.


Steps that the included tool performs:

First step tool does is ask soc type. (intel or MTK) for this guide it needs to be intel.

1. Guides user through the bootloader unlock steps.
adb reboot fastboot
verifies the status of unlocked or not
verifies the ability to do unlock in not already unlocked
fastboot flashing unlock
fastboot format userdata
fastboot format cache
fastboot reboot

2. Fastboot boot generic CWM recovery. To use its root shell for copying devices boot.img and recovery.img
3. Use Carliv Android Image kitchen tools to unpack the pulled boot.img and recovery.img
RECOVERY
4. copy adbkey.pub from pc running the patch to stock-recovery\ramdisk\data\misc\adb\adb_keys
copy adbkey.pub from pc running the patch to stock-recovery\ramdisk\adb_keys
this s done to ensure an authorized adb connection to device even after factory reset and data format
5. Edit recovery\ramdisk\default.prop as follows:
"ro.secure=1" to "ro.secure=0"
"ro.debuggable=0" to "ro.debuggable=1"
"persist.sys.usb.config=mtp" "persist.sys.usb.config=mtp,adb"
add line: persist.service.adb.enable=1
add line: persist.service.debuggable=1
6. Use Carliv Android Image kitchen tools to re-pack recovery
BOOT
7. copy adbkey.pub from pc running the patch to stock-boot\ramdisk\data\misc\adb\adb_keys
copy adbkey.pub from pc running the patch to stock-boot\ramdisk\adb_keys
this s done to ensure an authorized adb connection to device even after factory reset and data format
8. Edit boot\ramdisk\default.prop as follows:
"ro.secure=1" to "ro.secure=0"
"ro.debuggable=0" to "ro.debuggable=1"
"persist.sys.usb.config=mtp" "persist.sys.usb.config=mtp,adb"
add line: persist.service.adb.enable=1
add line: persist.service.debuggable=1
9. Edit boot\ramdisk\*fstab* as follows:
"forceencrypt" to "encryptable"
10. Add these lines to boot/ramdisk/init.rc after the line that starts: "on init"
# root use Permissive
write /sys/fs/selinux/enforce 0
11. Swap sepolicy and /sbin/adbd with permissive (insecure) versions included in tool "/img" folder
12. Use Carliv Android Image kitchen tools to re-pack boot
CWM
13. Use Carliv Android Image kitchen tools to unpack the generic CWM
14. copy stock-recovery\recovery.img-kernel to unpacked generic CWM folder (replacing file that is there)
copy stock-recovery\recovery.img-second to unpacked generic CWM folder (replacing file that is there)
15. Use Carliv Android Image kitchen tools to re-pack CWM
SECOND / FLASH MENU
16. fastboot boot patched boot.img
used to verify patched image does not cause device to brick
17. fastboot flash boot patched-boot.img
flashes patched-boot (user must have verified boot image works in previous step)
then formats /data to remove encryption
18. fastboot flash recovery patched-recovery
stock recovery does not seem to work when booted, so test booting pached image not done
this modified recovery is needed to be able to get back to bootloader mode if trouble occurs.
19. Load patched CWM
loads patched recovery to be used to flash SuperSu and also to make device "back-ups"






Updated 2-4-2018 Multi-platform-patch-tool
==>>Multi-platform-patch-tool


Downloads Needed:
Download adb=fastboot 15 second instal == https://forum.xda-developers.com/showthread.php?t=2588979
Download intel drivers == https://software.intel.com/en-us/protected-download/385047/494732
Download SuperSu.zip == https://forum.xda-developers.com/apps/supersu/v2-64-2-66-supersu-mode-t3286120


Thanks:
@vampirefo for most of the needed parts to make this work. CWM, permissive su-policy, without that this would not be possible

@bluefirebird For the image unpack tool



Youtube video I found , of someone explaining how he used the files to root his device.

Video is from before patch tool written. Video was from when individual build files were available.
New method of patching individual device files , removes possibility of flashing files from wrong device.

History of this root method started in this thread.
https://forum.xda-developers.com/general/help/rca-voyager-rct6873w42-rooting-help-t3485625

 

[Grishak]

Tablet hangs on bootloader unlock screen due to the volume keys not responding. Also, on first connect with fastboot flashing unlock, tablet responds with power key every time unless unplugged from usb. Upon second attempt, the power button key issue stops, but the volume keys do not function on the bootloader unlock screen.

 

[mrmazak]

Tablet hangs on bootloader unlock screen due to the volume keys not responding. Also, on first connect with fastboot flashing unlock, tablet responds with power key every time unless unplugged from usb. Upon second attempt, the power button key issue stops, but the volume keys do not function on the bootloader unlock screen.

Are you using this with correct drivers?
And with working voyager tablet, with an Intel soc. This does not work with an m version tablet(mtk soc)

I never had problems with volume key not recognized

 

[Grishak]

It's the RCT6873W42 with the Intel Atom. I'll check the drivers, but it reads the power button, just not the volume buttons.

---------- Post added at 04:45 PM ---------- Previous post was at 04:28 PM ----------

I have verified driver installation. Fastboot will not recognize volume up or down. Power button is the only one registering a key event. (4) EV_POWER received.

 

[mrmazak]

It's the RCT6873W42 with the Intel Atom. I'll check the drivers, but it reads the power button, just not the volume buttons.

---------- Post added at 04:45 PM ---------- Previous post was at 04:28 PM ----------

I have verified driver installation. Fastboot will not recognize volume up or down. Power button is the only one registering a key event. (4) EV_POWER received.

What about the allow OEM unlock toggle in the developer options screen?

I do not know how to verify key presses as you refer to.
So cannot compare on my end.

There may be different versions released with same model number.

I will make note in the op with the model and build number of my tablet, and can also include a link to the thread where the boot.img was built and tested.

But your problem seems to be before you can even get to that point.

 

[Grishak]

OEM Unlock is enabled. This is my fourth android root, I have yet to ever run into an issue with the volume keys not registering during fastboot. The confirmation screen to unlock the bootloader is visible, but I am unable to select yes or no. The only button that functions is the power key, it times out after 70 seconds. Perhaps if there were a way to extend that timeout period, the volume keys could function. I have attempted removing the usb cable after initiating the flash unlock command, also plugging it into an alternative charger, removed and entered headphones to trigger the volume control. I turned up a search on an individual that had an issue with RCA not programming the volume keys into the Bootloader Unlock screen. Different model, but that was the only thing I managed to find. Strange.

 

[mrmazak]

OEM Unlock is enabled. This is my fourth android root, I have yet to ever run into an issue with the volume keys not registering during fastboot. The confirmation screen to unlock the bootloader is visible, but I am unable to select yes or no. The only button that functions is the power key, it times out after 70 seconds. Perhaps if there were a way to extend that timeout period, the volume keys could function. I have attempted removing the usb cable after initiating the flash unlock command, also plugging it into an alternative charger, removed and entered headphones to trigger the volume control. I turned up a search on an individual that had an issue with RCA not programming the volume keys into the Bootloader Unlock screen. Different model, but that was the only thing I managed to find. Strange.

I did see that same issue with an earlier release on an rca tablet.

My build number is :
RCT6873W42-ANDROID6.0-V19-V1.16.50-E04
Kernel:
3.14.0+
Patch level:
June 1, 2016


Also the directions I had when unlocking was to hold volume up button before giving the "fastboot flashing unlock" command to avoid a timing problem.
I did not have the problem either way.

 

[Grishak]

https://forum.xda-developers.com/android/general/firmware-rca-viking-pro-rct6303w87dk-t3325158

That RCA Viking Pro tablet, that was the reference to the volume keys not being programmed.

---------- Post added at 10:34 PM ---------- Previous post was at 10:01 PM ----------

Android Version: 6.0.1
Kernel Version: 3.14.0 Aug 22 19:31:40 CST 2016
Build number: RCT6873w42-ANDROID6.0-V31-V1.17.70-W01
Patch Level: June 1, 2016

 

[Grishak]

I had a dream that it was an SD card holding me back. Sure enough, there was an SD card installed in the tablet which was preventing me from unlocking the bootloader. So as of now, it is unlocked and I will proceed with your directions and post an update shortly.

 

[Grishak]

After flashing the modified boot file on step B, my tablet screen is black with the backlight. I can not interact with the tablet except for volume down disconnecting the device and turning the backlight off. Also
error: device unauthorized.
This adbd's $ADB_VENDOR_KEYS is not set;
So basically if the authorization for ADB is gone AND my screen is gone...

 

[Wphall]

I have the RCA Voyager RCT6973W43 will this work on it

 

[Grishak]

I have the RCA Voyager RCT6973W43 will this work on it

Well I have the same model, my screen is now useless after unlocking the bootloader and flashing the first image. Am now searching for a new tablet. The issue immediately began right after rebooting from the successful flashing. Black screen, android set up the os and configured itself, screen still inactive. Debug is disabled now and I have no way to access the tablet via ADB/fastboot now. Out of ideas.

Update

After attempting to blindly access recovery *nothing will display on screen* and I have learned that my volume down button shuts off the screen and disconnects the tablet from my pc for a moment. Also I am positive the touch screen is no longer active, windows picks up the tablet as a storage device. I am thinking that it is the end of for this tablet.

 

[mrmazak]

Well I have the same model, my screen is now useless after unlocking the bootloader and flashing the first image. Am now searching for a new tablet. The issue immediately began right after rebooting from the successful flashing. Black screen, android set up the os and configured itself, screen still inactive. Debug is disabled now and I have no way to access the tablet via ADB/fastboot now. Out of ideas.

Update

After attempting to blindly access recovery *nothing will display on screen* and I have learned that my volume down button shuts off the screen and disconnects the tablet from my pc for a moment. Also I am positive the touch screen is no longer active, windows picks up the tablet as a storage device. I am thinking that it is the end of for this tablet.

;;

That is unfortunate. I would have expected you to stop when knew the build numbers and kernel versions were different.

recovery has nothing to do with the boot.img, so your stock recovery should still be there. From powered off hold volume button closer to the usb cable, and the power button for about 10 seconds. the wait for the warning screen to count down. (30 seconds)

should be at recovery.


Do you have the bootloader untrusted screen after unlocking.?
What do you mean "android set up the os and configured itself" ?
did you do the userdata format? that is needed to decrypt the tablet. as the /data area from factory is force-encrypted.

 

[Grishak]

Basically after unlocking the bootloader and flashing the first image... my tablet screen has been rendered useless. It is completely unusable and all of this happened before you posted the version number.

---------- Post added at 12:28 PM ---------- Previous post was at 12:26 PM ----------

I followed all instructions described up to the end of Step B. Upon completion of step B, my tablet screen has been rendered useless. Either it conveniently died at the worst time, or something during the flashing caused it. Either way, I have removed the battery, checked connections and can't find anything. Backlight, black screen. 24/7 can't get anything else to display. Can't do a thing with it.

---------- Post added at 12:32 PM ---------- Previous post was at 12:28 PM ----------

Well, I hope this brick helps others not make the same mistake, LOL!
I picked up the tablet for $20 months ago and have been waiting for a root.
Now it's dead so I guess it's time for a better tablet until this one is on sale again!

 

[vampirefo]

I have the RCA Voyager RCT6973W43 will this work on it

No, this root is device specific.

Sent from my Life_Max using Tapatalk

---------- Post added at 08:50 AM ---------- Previous post was at 08:49 AM ----------

Basically after unlocking the bootloader and flashing the first image... my tablet screen has been rendered useless. It is completely unusable and all of this happened before you posted the version number.

---------- Post added at 12:28 PM ---------- Previous post was at 12:26 PM ----------

I followed all instructions described up to the end of Step B. Upon completion of step B, my tablet screen has been rendered useless. Either it conveniently died at the worst time, or something during the flashing caused it. Either way, I have removed the battery, checked connections and can't find anything. Backlight, black screen. 24/7 can't get anything else to display. Can't do a thing with it.

---------- Post added at 12:32 PM ---------- Previous post was at 12:28 PM ----------

Well, I hope this brick helps others not make the same mistake, LOL!
I picked up the tablet for $20 months ago and have been waiting for a root.
Now it's dead so I guess it's time for a better tablet until this one is on sale again!

Bricking your tablet would be the expected outcome, as this root was never ever meant for your tablet.

Sent from my Life_Max using Tapatalk

 

[Grishak]

Looks like I'll have a nice battery and screen for a raspberry pi.

 

[icaruspony]

No, this root is device specific.

Sent from my Life_Max using Tapatalk

---------- Post added at 08:50 AM ---------- Previous post was at 08:49 AM ----------


Bricking your tablet would be the expected outcome, as this root was never ever meant for your tablet.

Sent from my Life_Max using Tapatalk

I was rooting my tablet from "out of the box" according to the directions, and everything was fine up until the same point. After flashing the modified boot img, formatting userdata and cache, and issuing the fastboot reboot command, now all I get is a backlit screen. Volume down does turn the screen black for a moment then lights back up. The pc sees it as a flash drive, but adb devices doesn't see it at all (not even as an unauthorized device).

My tablet is the correct model. RCT6873W42

I haven't figured out how to get into the recovery. Holding volume up + power, etc doesn't do anything.

---------- Post added at 09:33 AM ---------- Previous post was at 09:17 AM ----------

Looks like I'll have a nice battery and screen for a raspberry pi.

I'm having the identical problem on the identical step you did, and I have the correct model/version.

 

[mrmazak]

I was rooting my tablet from "out of the box" according to the directions, and everything was fine up until the same point. After flashing the modified boot img, formatting userdata and cache, and issuing the fastboot reboot command, now all I get is a backlit screen. Volume down does turn the screen black for a moment then lights back up. The pc sees it as a flash drive, but adb devices doesn't see it at all (not even as an unauthorized device).

My tablet is the correct model. RCT6873W42

I haven't figured out how to get into the recovery. Holding volume up + power, etc doesn't do anything.

---------- Post added at 09:33 AM ---------- Previous post was at 09:17 AM ----------



I'm having the identical problem on the identical step you did, and I have the correct model/version.

All I can think to do at this point is to add an md5 to verify the files downloaded are the ones intended to be used.

 

[vampirefo]

It would seem before people try to root their device they should first know and be able to get into recovery before they attempt to root.

If you can't get into recovery via hardware keys, there is no point to continue trying to root your device until you figure that part out.

I don't have the exact tablet in this thread, Mine is close enough though.

to get into my recovery.

press and hold volume down and power until splash screen pops up, I get a splash screen just before count down screen, release and when 30 second count down finishes tablet boots into recovery.

 

[icaruspony]

It would seem before people try to root their device they should first know and be able to get into recovery before they attempt to root.

If you can't get into recovery via hardware keys, there is no point to continue trying to root your device until you figure that part out.

I don't have the exact tablet in this thread, Mine is close enough though.

to get into my recovery.

press and hold volume down and power until splash screen pops up, I get a splash screen just before count down screen, release and when 30 second count down finishes tablet boots into recovery.

I have 49 more of these tablets, still in their boxes, to test with.