Why will my phone not turn on?

Yesterday, my phone turned off randomly while plugged in using the adapter and cable that came with the phone. I was using it normally, have never dropped it, and only minorly cracked the glass on the camera. I tried all the steps on the Nexus Forums for a phone that will not power on and recieved no feedback from the 5X.

I tried to turn it back on a couple minutes after it shut off, and I was able to get the white Google logo, bu then it reverted back to being off. A couple hours later, I was able to get the bootloader up, and I set it to start, got the white Google logo, and then it went back to being off. Just this morning, I tried first to get the bootloader up and then to turn it on. I was not able to get the bootloader up, but I was able to get the white Google logo and have it turn off again.

The Google Store (place of purchase) has said that if I send it back to have it replaced, I will probably have to pay full price for a new OR possibly refurbished 5X bacause of the camera crack. Any suggestions on what might be wrong, what I could try on my own, or what to do would be greatly appreciated. Thank you.