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14th November 2012, 03:54 PM |#10  
Junior Member
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Originally Posted by sharpened_edge

If you could expand on what you did? I have changed the file extension back on the file in question. My problem is that since I failed the update, the system says no update available and I am stuck on 4.1.2

Ok i'll try.

Sorry for my bad english

I'll do a step by step howto.

First of all you'll need to download the 4.1.2 FW from Google.
Make sure, you choose the right one.
Take your Nexus 7, go into settings---> About Tablet and look for the Build-number.

Google OS

Then you will have to download this Tool (SGStoEXT4)
(This Tool will extract the Image into a mountable (readable) Image.)

Then you download THIS
(This Tool will mount your Image and you'll get access to the orig. Systemfiles you need.)

Ok lets begin:

Once you've dowloaded the Firmware 4.1.2 (Not 4.2 !!). It should be a .tgz. Just rightclick it, and extract it into a new Folder.

In this new folder you'll see a .zip File. Extract this too by choosing "Extract here".
Now there is a File called SYSTEM.IMG. This is File you'll gonna need!

Now open the downloaded Zipfile "" and doubleclick the .jar to start it.

You'll see a window that pops up. Drag and drop the SYSTEM.img into this window and it will extract the .img into a File called "system.ext4.img" which is built right in the same folder, the system.img is.

Now install the second Tool you've dowloaded called "Linux-Reader" and start it.
Once you startet it, choose "Mount Image" on the left hand side.

Let everything like it is and click Next.

Choose the system.ext4.img by doubleclicking it.

Now you should see the mounted Image called "Linux Ext Volume 1"

If you doubleclick it, there are all the original files from 4.1.2.

Create a new Folder on your PC and call it Systemfiles (or whatever).

Go back to Linuxreader, mark all files and folders (Strg+A) and rightclick them and hit "Save".

Now click "Next" and choose the Systemfile-Folder as the Outputfolder.

You're already done.

Copy the new created Systemfile-Folder to your Nexus7 (in the dowloadfolder threre, for instance)

Start the Updateprocess and wait till it stops with the currupted File error.

For example:

Finding update package...
Opening update package...
Installing update...
Verifying current system...
assert failed: apply_patch_check("/system/app/BrowserProviderProxy.odex", "21a89
E:Error in /cache/
(Status 7)
Installation aborted.

Write down the path (marked redcolor in the example) and search for it in the new Systemfile-folder.

The path in the new Systemfilefolder will be the same as it shows on the updatefailure.

Replace the corrupted File with the one of your fresh extracted ones using Rootexplorer on your Nexus 7.

Start the Updateprocess again.

If there is another corrupted File error, replace that File too.

Once you replaced all corrupted Files, you're done.

I replaced 4 Files before the update runned through properly.

I hope this helps and please let me know if it worked 4 u.

Last edited by DroidBonzai; 14th November 2012 at 04:49 PM.
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