you purchased from newegg, you have to go through newegg. if you have sprint insurance you may be able to pay a deductible and get a refurbished model, but i think if you do a factory reset you will be ok. sounds like something locally on your end that can be fixed by factory resetting. sprint has a 14 day return and you are past that. now you are in insurance replacement/htc warranty phase.
i recommend to use google and not htc/dropbox. they both save nearly all the same data but google is proven...