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.
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?