Sounds like you flashed a ROM for the wrong model. I'm not an expert on going back to stock for this phone, since I've had it for only a couple of weeks. There is a lot of info in the LG G2 XDA forum on reflashing stock. My advice: research before doing anything further with your phone, and then follow the recommended steps very precisely. In the meantime, charge it to 100%. EDIT: Did you make a nandroid backup of your original stock ROM before flashing the new one? If so, you could factory reset and restore, both using TWRP.
Sent from my VS980 4G using xda app-developers app