Apple Watch ultra charging issue
Post Update to 26.2 or applicable ios my latest Apple Watch Ultra not getting charge fast
Apple Watch Ultra 3
Are you using at least a 20W Apple power adapter and the USB charging cable which came with the Apple Watch?
Did you try to force restart your watch?
To force restart your watch, press and hold the Digital Crown and the Side button together for about 10sec, until the Apple logo comes back again.
If your Apple Watch won't turn on or won't charge - Apple Support