Can be fixed short term by puttin freezer
Put it in the freezer in a Ziploc bag. Wait about an hour. Should boot normal. But will give u a short window to get files off. Once chip starts heat up, jumps into boot loop again. I had good luck sandwiching phone between 2 big ice packs and using my laptop with usb. micro cable download all files needed.
LG knows of the boot loop issue. It's seems to be a batch where the processor becomes loose from the motherboard. Heat gun and sticking freezer are quick very short term solutions. LG will replace phone or board no real questions asked.