Your efforts are appreciated and I'm here to help. Has your phone been exposed to any physical/water damage? When did the problem begin? Please tell me more. AyaniB_VZW
This is likely the notorious "bootloop" issue that has plagued LG G3 and LG G4. Google search it for details, but basically LG used an inferior method to soldier the chips on the phone with. Over time it would get hot enough that the soldering would come loose. The phone either would boot over and over or eventually go dark and not boot up. There are some crude fixes for "bootloop" online but they are a bit crude.