Semi-Dead Phone

Yesterday, my groupmates and I were presenting this VR application to our panelists. Somehow in the middle of the demo, my phone rebooted and it took a while before it actually opened. After it opened though, a few seconds or about a minute later it will reboot again and this happened a few times so I decided to turn it off. Later, when I decided to turn it on again it won't let me past the LG logo and it just keeps on bootlooping so I decided to turn it off by removing the battery and let it stay off for a while. Again when I decided to check on it, the phone won't even turn on even after holding the power button for a few seconds and trying to remove battery and place it back. I decided to check on it later again and it would boot but only until the LG logo again and this time it stays there for a few seconds and then it goes black and this just keeps on happening every time I try opening it. I even tried to do a hard reset (reset to factory settings) but only the same thing happens, the phone freezes at the "Yes" option when doing the factory reset and it goes to black after a few seconds. I even tried flashing a firmware but it won't let me do it because the same thing happens (reboots into LG logo, freezes and then turns black).

What could have happened? Is there anyway to fix this? :/
Any help would be greatly appreciated.