Sounds like you rinsed all the oil out of the poor thing then turned it over and it grabbed at top dead center.

Give it a good squirt of oil through the glow plug. You could remove the back plate and get some in there too. Mount a prop, and turn it over.

Heat will help, as noted. Careful you don't use flammable oil such as wd-40

... at least that's what I'd do.

Then get some after run oil from the hobby store and douse it well.