can you kick it? if so you know its fine with compression. try roll starting it?
my mate's compression somehow seized....and we had to back it off. don't know if he did it cause he's a butcher, or it kinda siezed somehow by itself, but pull the left side of the engine case off and check u can move the compression wheel if u can't kick it. if it doesn't move...you may have to losen the main bolt. not to sure if thats the smartest thing to do, but the only way we could fix my mates Atomic. Good Luck buddy.