Battery Issues

Hi! First post on Reddit so please forgive me if there are things I miss. I just bought a used Onewheel pint the other day with about 170 miles on it, everything worked great, tested it out a bit, then left it in the car while I was at work. I get home and attempt to ride it home from my parking spot (about a mile) and it’s got an isssue of battery temp too cold. I let it warm up with the heater in my car, and when I turn it on it’s at 2% battery (was 100% when I left for work). I make it home, charge it up, take it out the next day and when I turn it on, same thing, battery is below 10% and drops to 1% very quickly. I go up and plug it back in, charges to 100% within 20 minutes. Same thing happens each time I ride it. I’ve left it plugged in for over 24hours as well and no fix. Using a regular charger. If anyone has any clue how to fix this please let me know!