Theragun mini percussive massager won't turn off / on

I can't tell if this Theragun mini is supposed to be on or off. If it's on, because the green LED is on, then I technically cannot turn it off. But it won't massage at all, so I guess technically it doesn't turn on either. I tried to do a long-press on the power button, tried many short presses. Maybe it was plugged into the Theragun mini charger for too long. The green LED stays on regardless of how long the button is pressed. I also tried plugging it back into the charger to see if that did anything, but it did not. I was hoping to open it and take the battery out to reset it, (battery removal = no power = turns off, one would think) but I don't know how to open it. If anyone has a link to a disassembly let me know. I couldn't find where to take it apart in the instructions.