After trying every single tutorial presented on this forum I gave up. Returned it back to the 4.2.2, unrooted, blocked the bootloader, upgraded to the 4.3 to generate the original error and called tech support. I will return the thing and get a new one.
I'm most certainly sure the problem lays on the baseband, something with the first 4.3 upgrade damaged files and the system isn't able to rebuild itself, and I couldn't find a way to do it manually.
Unfortunately I will avoid upgrading it to the 4.3 untill google says something about this bizarre bug that is making several people go nuts with android.