Installing stock Android on Galaxy S3 fails. How to see why? I have tried installing AUT-I9300XXUGNA5-20140129183554.zip and O2U-I9300XXUGNA5-20140224162541.zip on my S3. They both fail with "Installation aborted", but I have no problem installing cm-10.1.3-i9300.zip. I have tried both from external_sd and sideloading. Same problem.

I can see the information from the screen in /tmp/recovery.log:

-- Installing: /external_sd/O2U-I9300XXUGNA5-20140224162541.zip
Finding update package...
I:Update location: /external_sd/O2U-I9300XXUGNA5-20140224162541.zip
Opening update package...
Installing update...
Installation aborted.


The most prominent difference between AUT&amp;O2U and cm-10 is size: The AUT&amp;O2U are around 1 GB whereas cm-10 is around 200 MB.

Can I somehow do the installation by hand through the shell, so I can see exactly why the two zips fail to install?
You can't install the stock ROM zip like as custom rom. Extract the stock rom zip and you will get the .tar PDA file to flash via ODIN. Download ODIN 1.85 and also install Samsung USB driver and then reboot your phone in download mode by pressing three combo key VOL Down+ Home+ Power button. Now connect it to pc while ODIN is opened on PC. Now your phone should show up on some port and usind PDA button and browse the firmware you extracted from the zip on pc and select it and flash. You will loss the root by doing this and also all data will be wipe out.