My tablet does not boot anymore, need expert help - or firmware

[alcoholic]

Hello,

the tablet (Lenovo LePad) was rooted with z4root, but I have run the "unroot" option, and now the tablet is stuck at the boot logo.

I have investigated already, but I do not have enough experience to say what is wrong. It appears that file permissions prevent reading some files, e.g. the DalvikVM cannot start up. I have attached the output of mount, dmesg and logcat - maybe an expert can tell me what is wrong?


I saw some scripts in /etc which use busybox, but when z4root performs "unroot" it deletes /system/bin/busybox - could this be the problem? I am not sure the scripts are used at startup.

I managed to copy the binaries for busybox, su and rageagainstthecage to the device (the only writable place I found was /data/appstore). I can run rageagainstthecage, but busybox and su give the error "cannot execute binary", even after copying them with dd to /system/bin and running chmod 4755 on them. I notice that an already present binary gives the same error message (/sbin/rm). There appears to be a permission problem, but I have not found a way of viewing permissions of files and directories using adb and the shell.
I'd be happy if someone with a working LePad could send me their logcat, dmesg and mount output so I can compare to mine in order to understand where things go wrong...


I don't know how to proceed at this point. Does anyone have the firmware flash images so I can use fastboot to flash the pad to its original state? The exact description for the pad is: Lenovo LePad Y1011, version LePad-001n.


Any help much appreciated!

 

[alcoholic]

Hello,

I was finally able to fix this.

What went wrong? z4root assumes the files it pushes into /system subdirectories were not present prior to rooting. For the LePad this is not true for /system/bin/busybox ; a good many commands in /system/bin are actually symlinks to the busybox binary. When I performed the "unrooting" z4root deleted this binary, and the pad would not start properly.

How did I fix it? I extracted rageagainstthecage and the su and busybox binary from the .apk of z4root (attention, despite the naming su and busybox are actually gzipped, so the have to be unzipped once more to become executable binaries). By luck I found a place that was writable (/data/appstore - this is normally mounted to the sdcard, I guess, but wasn't because the boot process could not complete). I pushed the files there, ran rageagainstthecage, became root, remounted /system as writable and put /system/bin/busybox back. Afterwards, the pad would boot.

Bottom line: Do not unroot with z4root on the LePad. If you want to unroot, do this manually...

Hope this saves someone some gray hairs...

Cheers...

 

[shimtronics]

Hey alcoholic thanks for your instructions....

But I cannot get my device to work with adb!!! iT DOES NOT RECOGNISE MY DEVICE...


Can you please give me specific instructions on how to solve this problem please please!!!!!!!

 

[alcoholic]

Hey alcoholic thanks for your instructions....

But I cannot get my device to work with adb!!! iT DOES NOT RECOGNISE MY DEVICE...


Can you please give me specific instructions on how to solve this problem please please!!!!!!!

Hello shimtronics,

adb did not list the device on Windows. It did work on Linux (I used Ubuntu and the LEOS SDK Lenovo provides). Good luck!