My Nexus 5 Won't Power On. What is Happening?

[AC Question]

My Nexus 5 (running on Android Marshmallow 6.0.1) randomly shut down and won't power on. It charges just fine. If I hold the power button down it says "Google" and then goes to the moving dots thing like it usually does when powering on, but they keep going on forever. I went to Fastboot mode, then went to "Recovery Mode" and did "Reboot system now" but it just does the same thing. Any ideas on how to fix this? Also, in Fastboot mode, I noticed and option that said "Restart Bootloader" and I was wondering what this does.

 

[B. Diddy]

Welcome to Android Central! The firmware might have become corrupted, or there could be a hardware failure. Have you already tried wiping the cache partition or doing a factory reset from the Recovery menu? http://forums.androidcentral.com/nexus-5-rooting-roms-hacks/352008-guide-nexus-5-recovery.html