The LG G2 is old enough to need a new battery. Feb 2014. So the long shot and cheap thing it could be is the battery. Pop a new one in and let it charge overnight and only then try to turn it on.
My phone has a glitch these past few days, the home screen would automatically change into default one. This morning, my phone won't stop blinking and the home screen started to change, but it keeps changing non-stop, so I took out the battery and boot my phone, but it won't turn on. I tried several times, still no result. I tried recovery mode, I got into recovery mode but even after recovery mode my phone still stays on LG logo! I need your advice and help since I can't afford to buy a new phone right now and I need my phone!