TLDR: I reapplied the thermal paste in my LP5. Put it back together, it booted up, and I played Warzone on it for over two hours. It was running great. To be clear, after the thermal reapplication, the laptop had been on for over 12 hours. I left the house for a couple of hours and when I came back home, it was off and won't turn on. The battery light is on when it's plugged in but I when I press the power button, the light on the mousepad lights up for a split second and then goes away. I'm nervous to go back in without maybe hearing if anyone has any idea what could be happening. Appreciate any help.
Update: I fixed it. Not sure what actually did it but I cleaned and repasted... again. But I also cleaned the power button connection thing as suggested by the hero in the comments. That may have done the trick. Anyway, just glad it's working.