Series Three watch stuck in boot loop after asking to erase all data - repeatedly

So this has happened before and I can't remember how I got around it.

It won't get past the Apple logo when it's off the charger... and when it's on the charger I'll get the logo.... then the 'loading' circle. About halfway it'll tell me that erasing content back to factory settings is required. I can either select Okay or cancel. If I cancel it just loops again and eventually asks once more. If I select okay, it'll load, restart, and begin again. it's unpaired from my phone and I can't get any further than this loop. HELP!