okay so i feel your problem. iv tried and tried and tried different things and not locks no luck.
the one thing i havent tried is going to a pre gps rom and then to a gps rom. so if u went from the off. vzw 6.1 update to a custom gps rom your gps wont work. the only reason i haven tried this yet is because i havent found a good help thread about doing it via usb only. im afrade to use the meathod of flashing using sd card. so if someone has one a big thanks i advance.
just something i started at but didnt end up finding what i wanted hope it helps man
http://forum.ppcgeeks.com/archive/in...p/t-30718.html
if u try this let me know how it goes on the account if im to much of a noob to try (and scared)