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[Q] Ematic EGS004 BU Rooting/Kernal Module Issue

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rivkah613
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Default [Q] Ematic EGS004 BU Rooting/Kernal Module Issue

Hello,

Veteran SW guy here; but newbie at Android.

I have three tablets. All of them are Ematic Model EGS004. All three were bought for the sole purpose of being used by children to watch educational videos (in mp4 and flv formats) and read PDF documents. Absolutely nothing else. No games. No internet access whatsoever. Etc.

Two of the tablets are still in the box and have not been touched. I'm hoping that they may be useful for making/restoring an original image of the tablets.

To implement the requirements of this project, I did the following to one of the tablets:

1) Used the instructions at http://forum.xda-developers.com/show....php?t=2495069 to get root access with Cydia Impactor and Chainfire SuperSU.

2) Installed Titanium Backup (root). Using this, I uninstalled most of the Google applications (excluding Google Play), messager, YouTube, games, etc.

3) Installed File Manager (Explorer) by Rhythm Software.

4) Installed Shell Terminal Emulator by MobilDev. Using the shell, I went to the /system/lib directory and renamed libwifidisplay.so
and libwpa_client.so to libwifidisplay.disabled and libwpa_client.disabled.

Unfortunately, upon reboot, the tablet gets stuck in the bootup screen (with the ematic logo). Obviously, something about Android causes a hang if an expected kernel module is missing...

I tried using the shell in Cydia Impactor. But, the file system was read only. I tried:

mount -o rw,remount /system

But, I get an "Operation not permitted" since I am not root.

I downloaded the ADB bundle for windows at http://developer.android.com/sdk/index.html#download and successfully installed adb on my PC. I could get into a shell with the "adb shell" command. But, the /system/lib directory still is read only and I can't seem to remount it since I am not root.

I tried "adb remount". "Operation not permitted" was the result, again.

Cydia Impactor installs its "su" binary in /system/xbin. I tried running it from there using various invocations like "su -c mount -o rw,remount /system" Each time, the shell hung and I never got a shell prompt afterwards.

Questions:

1) Surely there's a way that I can get back in to rename these files now... I can "ls" them from the adb shell. I can pull them to my PC with adb pull. (adb put doesn't work either since the file system is read only.) Ideas?

2) Once I get this solved, what is the best way to get rid of the wireless capability so that children can never use it? I would like to move videos and PDF's between it and a PC strictly via USB.

3) Is there a way to image/restore one of the untouched tablets - or, for that matter, this one once its up and running like it needs to be?

Thanks everyone!
Jim
 
rivkah613
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Let's try a simpler question since there have been no responses:

Once I get into a shell (non-root) using ADB or Cythia Impactor, I believe I can rename the files if I can only get SuperSU to work. However, when I invoke su, the shell hangs:

su -c ls
su

etc. All of these hang. I assume that SuperSU is waiting for a confirmation from the android display. But, since I'm stuck at the startup screen, there's never an opportunity. How can I get the shell to interact with me as root so that I can remount the file system as RW and rename files?

Thanks,
Jim



Quote:
Originally Posted by rivkah613 View Post
Hello,

Veteran SW guy here; but newbie at Android.

I have three tablets. All of them are Ematic Model EGS004. All three were bought for the sole purpose of being used by children to watch educational videos (in mp4 and flv formats) and read PDF documents. Absolutely nothing else. No games. No internet access whatsoever. Etc.

Two of the tablets are still in the box and have not been touched. I'm hoping that they may be useful for making/restoring an original image of the tablets.

To implement the requirements of this project, I did the following to one of the tablets:

1) Used the instructions at http://forum.xda-developers.com/show....php?t=2495069 to get root access with Cydia Impactor and Chainfire SuperSU.

2) Installed Titanium Backup (root). Using this, I uninstalled most of the Google applications (excluding Google Play), messager, YouTube, games, etc.

3) Installed File Manager (Explorer) by Rhythm Software.

4) Installed Shell Terminal Emulator by MobilDev. Using the shell, I went to the /system/lib directory and renamed libwifidisplay.so
and libwpa_client.so to libwifidisplay.disabled and libwpa_client.disabled.

Unfortunately, upon reboot, the tablet gets stuck in the bootup screen (with the ematic logo). Obviously, something about Android causes a hang if an expected kernel module is missing...

I tried using the shell in Cydia Impactor. But, the file system was read only. I tried:

mount -o rw,remount /system

But, I get an "Operation not permitted" since I am not root.

I downloaded the ADB bundle for windows at http://developer.android.com/sdk/index.html#download and successfully installed adb on my PC. I could get into a shell with the "adb shell" command. But, the /system/lib directory still is read only and I can't seem to remount it since I am not root.

I tried "adb remount". "Operation not permitted" was the result, again.

Cydia Impactor installs its "su" binary in /system/xbin. I tried running it from there using various invocations like "su -c mount -o rw,remount /system" Each time, the shell hung and I never got a shell prompt afterwards.

Questions:

1) Surely there's a way that I can get back in to rename these files now... I can "ls" them from the adb shell. I can pull them to my PC with adb pull. (adb put doesn't work either since the file system is read only.) Ideas?

2) Once I get this solved, what is the best way to get rid of the wireless capability so that children can never use it? I would like to move videos and PDF's between it and a PC strictly via USB.

3) Is there a way to image/restore one of the untouched tablets - or, for that matter, this one once its up and running like it needs to be?

Thanks everyone!
Jim
 
godlessfather
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(Last edited by godlessfather; 28th February 2014 at 12:30 PM.) Reason: Updated
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Quote:
Originally Posted by rivkah613 View Post
Let's try a simpler question since there have been no responses:

Once I get into a shell (non-root) using ADB or Cythia Impactor, I believe I can rename the files if I can only get SuperSU to work. However, when I invoke su, the shell hangs:

su -c ls
su

etc. All of these hang. I assume that SuperSU is waiting for a confirmation from the android display. But, since I'm stuck at the startup screen, there's never an opportunity. How can I get the shell to interact with me as root so that I can remount the file system as RW and rename files?

Thanks,
Jim

I rooted my son's EGS004, installed busybox, and played around with it without any apparent problem. When I rebooted it, I was prompted to set up the device then and every subsequent time I rebooted it. I could not install any apps and could not redo the Cydia Impactor rooting procedure. The reason was that /data was reporting itself as 0.00B in size. Factory reset didn't change anything. Ematic wants me to return it.

Your issue sounds different, but it could be something as simple as the device being very unforgiving. There's a pinhole with a reset button (never worked for me but tech support suggested it) which may help.
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