If u got it backed up, wouldnt hurt. Have u scanned your phone and cpu for viruses?
When I broke my s2 screen, I did a blind reset, and after it I was able to hook it up to the cpu. This definitely is not a new issue. I've googled in the past and found a lot of different suggestions. The more sh1t u try, Sprint may end up just replacing it. Did they hook it up to their own cpus at the store?
not sure, they just replaced the port cuz it wouldnt charge
