I've reseted the MB501 but this phone is hardlocked (user entered to many times wrong subsidy code) so phone now dont detect ANY SIM CARD and don't ask for 'special code' for unlock whe you put a non-tmobile sim.
I've handled to bring the special code screen with this code
#073887* but phone don't accept unlock code anymore. Always says unsuccessfully unlock try.
So until now no solution for hardlocked CLIQ XT Motorolas.
My two cents, hope someone can find a way to unlock this phone when is hardlocked.