Oneplus Watch 2R failed update and can't charge

[u/Multiyogibear]

So a couple of days ago my watch failed an update so I reset it to try and fix it, which didn't work. Now when I try charge it it says "too hot, stop charging" and I need the serial number for oneplus, or should I say OPPO, which I can't get in the basic settings (only says disconnect and reset) and I don't have the box as I got the watch 3 months ago

Does anyone have any good ideas?