They flashed on it 4.0.4 ICS and they unlocked the bootloader.
I update the system with OTA to 4.3 stock.
In order to try the Xposed Framework I used the Toolkit to take root access.
Then, connecting my Google account, when Play Store started to install all of my apps it prompted out an infinite list of error:
Flashed two times 4.3 stock via Toolkit, locked and unlocked, rooted and unrooted but... nothing.
Also tried to delete my account, delete play store data, delete framework data, wipe cache, wipe dalvik... nothing works.
Phone is uselss in this way... so if anyone has figured out what to do, please let me know.