I had the same problem. If you have the repair or replace coverage with sprint then this is covered under the wear and tear coverage. Sprint replaced my phone. Only problem is that my local repair center denied me service because they said it did not fall under wear and tear. They said it was physical damage. So in the end sprint had to send me a phone in the mail since they couldn't tell the repair center to follow their set guideline.
If you don't have any insurance coverage then under sprints new policy change the repair center can replace or repair your phone for a $35 fee if your within the 1 year warranty which I'm sure your in or you can send it to htc at no cost but that will take several days for them to fix it.
Just remember that this is wear and tear just like the keyboard on the tp or tp2. It uses the same type of spring loaded mechanism. Don't let the repair center tell you otherwise.
Good luck.
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