If it has a removable battery, then it’s likely made up of 18650 cells. If it isn’t then it’s likely a flat lithium cell like a phone.
I pulled the battery case apart and snipped all of the 18650s out and charged them in a dedicated charger. They had been sitting too long and some of them were far below where they should be. It was causing the laptop power adapter to shut off.
Once they were properly charged they all tested good again. I could buy new cells, but I think these will work fine for what it is.
Now I need to spot weld metal tabs back onto the cells, put it back together, and hope it works.