Virgin Mobile Desire 510 stuck on HTC screen

My Virgin Mobile HTC Desire 510 is stuck on HTC screen. I just got the phone in April and need it to last me 2 more months. It is not rooted. I removed the SD card and have tried everything including a factory reset to no avail. What are my options? I really need to get this working again ASAP. Someone somewhere mentioned something about "flashing" it, but I don't know what this means or how to do it, or if that will even help me with this issue.

Please help!

Edit: I should mention that my computer runs OSX 10.9.5 (in case I need to download some programs.)