Google Nexus 5 :: Phone Stuck At Bootloader?

I have a nexus 5 that I was preparing to hand down to my wife. I had transfered everything over to my new phone, and initiated a factory reset. It rebooted to the "erasing" screen, and sat there for about 20 minutes, before switching to the dead android screen (w/ red triangle.) I thought that was odd, did some searching, and tried the recovery mode from the bootloader. That produced the same results. So now I'm stuck.

From the boot loader I can access the following options:

Start -> Erases for ~20 minutes, then dead android
Restart Bootloader -> Screen goes blank, phone vibrates, and then back to the bootloader screen
Recovery Mode -> Erases for ~20 minutes, then dead android
Power off -> turns off the phone

I called Google, and the tech support hadn't heard of anything like this. Because it's almost two years old, he transferred me to LG's tech support, who basically said find a local repair shop, or they could RMA it for an unknown cost.I'm pretty sure the phone is bricked at this point, which is frustrating, because it was running stock android - completely unmodified. I think I might have rooted it once, months ago, but I can't imagine that that would have caused this issue. I had even received and installed Marshmallow OTA, and it was running perfectly.

Anyway, some program I might be able to use on the PC to regain access to my device.

Literally the only information I can provide about the phone at this point in time is as follows:
Product_Name - hammerhead
Variant - hammerhead D820(H) 32GB
HW Version - rev_11
Bootloader Version - HHZ12k
Baseband Version - H8974A-2.0.50.2.27
Carrier Info - None
Serial Number - 047....
Signing - Production
Sercure Boot - Enabled
Lock State - Unlocked