I had a broken GSM modem for years. I cannot find the link right now, but you have to disassemble, and then pop the metal cover off the GSM modem, and then glue small springs(read get spring, and cut it, as in one rotation), and put them back on the GSM modem, replace the metal cover, and then put the phone back together.

It worked for me, there was a thread on here about it,

with the other try a fresh re-flash. but I have really no clue with the USB failure.