Can't boot Verizon G3

Having major problems with my G3; started last night. I noticed that my phone was on the LG boot splash screen and was unresponsive. I reseated the battery and it seemed to be working fine after that. However a couple hours later it was completely dead. If I reseat the battery and turn it on now, The LG screen comes up for a couple seconds, then shuts off. Never get the Verizon screen. I tried to do a factory data reset on it, and get the menu but once I select Yes, the phone goes back to the LG screen for about 2 seconds then shuts off. I got it to go into TWRP once, but it shut off before I could do anything with it. It'll boot into download mode, and my system detects the COM port, but almost immediately the phone shuts down. The phone was running fine before this happened. Any thoughts? I'm really scratching my head over this one.

TLDR:
- phone rebooted last night, won't boot now. Keeps shutting off before I can get anywhere.