watch series 4 won't charge
I put my new watch on the charger this morning it drained the battery, now it won't charge and keeps restarting.
I suggest you start by testing with a known good charging cable and USB power adapter if you have them available. You should certainly have at least the adapter from your iPhone. Also try a different power socket in case the problem is on your wall, then see If your Apple Watch won't charge or it won't turn on - Apple Support