cant go to factory reset page on lg g2

[in 776]

so i recently decided to use my old lg g2 as a temporary phone cause my previous phone broke. however,as i havent used the phone in 2 years, i forgot the password and decided to factory reset it. but when i power off, press power button and volume down,it will keep going blacks creen and replaying the lg startup screen. the phone is unrooted so i cant do any other thing about it.
im looking for a solution before i go to the repair shop

 

[B. Diddy]

Welcome to Android Central! The battery might be failing. Try keeping it plugged into a wall outlet overnight, then try powering on again.