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[Guide] Unlocking Bootloader and gaining root on the A90 5G

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By triggz881, Junior Member on 25th December 2019, 11:46 AM
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Notes: This trips KNOX so you will void your warranty, read all the steps carefully before beginning, flashing can be dangerous if you do it wrong. Don't blame me if you brick your device.
Backup all of your data and settings before starting as you will need to reset to factory defaults during this process.
With that being said, the process is relatively straightforward and easy.
PS: my device is the A908B, there is also an A908N if anyone wants to test on that be my guest.

Needed:
ADB
SamFirm
Odin
Magisk Manager


Step 1 - Downloading your firmware.

Go to SamMobile SM-A908B
Find the correct firmware for your device according to country and operator.
Note: You can use generic country firmware instead, this will remove carrier added software and limitations but may remove features and disables OTA updates.
Note the 'product code'.
Now open SamFirm.
Type SM-A908B for model
In the region box type the product code you noted earlier.
Click Check Updates.
When it has found the firmware, make sure decrypt automatically is checked and then click download rom.
The firmware is around 4gb.

Part 2 - Unlocking the Bootloader

Go to settings > about phone > software information. Hit build number a bunch of times until you activate developer options.
Go back to settings > developer options
Enable OEM unlocking
Enable USB debugging
Turn off the phone
Hold volume up and volume down whilst inserting the USB cable
This should take you to the bootloader unlock screen.
Long press Volume up to unlock the bootloader.

Part 3 - Obtaining root

After SamFirm finished downloading the rom it should have extracted it into 5 tar files.
Copy the tar file beginning with AP to your device.
Download Magisk Manager on the device and install.
Press Install on Magisk Manager
Confirm the Install
Select the option 'select and patch file', then locate the APdjkfgrsdkfhgkjrg.tar.md5 on your device and select it.
Magisk will then patch the file and dump the patched version to your phone.
Copy the patched.tar to your PC
Reboot phone into download mode
Open Odin
For BL use the BL.tar.md5 file from stock firmware
For AP use the patched.tar file
For CP use the CP.tar.md5 file from stock firmware
For CSC use the CSC.tar.md5 file from stock firmware (not the CSC_HOME)
Press Start and wait for it to flash
After flashing, the phone will reset.
After initial setup, install magisk manager again.
Remove the USB cable and turn off the phone.
Turn on the phone by holding volume up and power, let go when you see the bootloader warning.
Open Magisk Manager Click Install.

Phone is now rooted.

Note: Powering on the device normally will disable root, you must hold volume up to power on the device to activate root.
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26th December 2019, 12:21 PM |#3  
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Going to put a few hours into compiling twrp tonight but this might take me forever, I'm really busy with work and I got 2 kids too so free time is scarce. So feel free to have a go at it yourself.
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28th December 2019, 10:50 PM |#4  
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After root activation with the volume button start up will the root persist? Can the device be restarted without any hidden key?


Thank you
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29th December 2019, 12:26 PM |#5  
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Yes the root persists, but every time you turn the phone off and back on again you will have to hold up to activate the root. Resetting the phone while root is enabled does not disable it though iirc.

More work done on twrp last night, nearly ready to attempt compiling.

Edit: So I made a device tree and compiled twrp fine. Unfortunately it needs a custom kernel to be able to boot. Working on this now.
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2nd January 2020, 08:31 PM |#6  
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Any further progress??
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14th January 2020, 10:40 PM |#7  
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No not really. I need to reach out to the twrp Devs of the S10 and see what modifications they did to theirs, but super busy at the moment. Sorry.
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21st January 2020, 07:16 PM |#8  
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Quote:
Originally Posted by johnoponi

Any further progress??

Ok so I made a lot of progress since last post. I'm compiling the kernel as I type. But the process takes a long time. If we are lucky it will boot twrp straight away if not I'll keep at it until I manage.
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27th February 2020, 05:11 AM |#9  
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Quote:
Originally Posted by triggz881

Ok so I made a lot of progress since last post. I'm compiling the kernel as I type. But the process takes a long time. If we are lucky it will boot twrp straight away if not I'll keep at it until I manage.


Are you still trying?
8th March 2020, 02:31 PM |#10  
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Failure on Model SM-A9080 (China Version)
Today I did this on model SM-A9080 but unluckily failed, and the OS could not be loaded, with boot loop on the phone.

Really the specified TWRP should be developed.
18th March 2020, 02:09 AM |#11  
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Quote:
Originally Posted by triggz881

Ok so I made a lot of progress since last post. I'm compiling the kernel as I type. But the process takes a long time. If we are lucky it will boot twrp straight away if not I'll keep at it until I manage.

Hey - did you manage to get anywhere with this? If you'd like help, i'd be happy to get stuck in. Could you put the code on Github?
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