I watch series 4 totally locked

Hi, I have a series 4 watch. I know the passcode but it doesn’t work. I reset the watch then it has come up as a passcode on the screen. Don’t know why but it has been unpaired for my iPhone also. I can not seem to find a solution to this nightmare I am having.

when I hold power button it just resets the watch and goes to the passcode screen again.

it won’t show up the power down option either so I can’t reset it again.

any help appreciated.