What is wrong with my HTC Desire 626s?

[AC Question]

Hi android central! To begin: here's some background. This phone is only about 8 months old. This issue only started two days ago and I have no idea how to fix it.
My Desire will boot up to the HTC screen and then shut off, then load to the HTC screen again and then shut off. If I'm lucky, it'll get past the MetroPCS screen and fully load to where I can use it. I'll tap on something, then it will freeze and then shut off. I've tried a soft reset, and a hard reset twice. I've taken out my SD card and left it to sit for a few hours. I have no idea what to do next.

 

[B. Diddy]

Welcome to Android Central! The battery might have failed. If you bought it new, it should still be under warranty. Contact HTC for repair or replacement.