the jammed flywheel is directly connected to the crankshaft's end..
What that means is the crankshaft and piston have to be jammed as well.
Have you determined that the flywheel itself what's causing the problem or could it be something to do with the crankshaft or piston? If not, the flywheel isnt the trouble and there's no need to pull it..
for instance, did you snap a piston ring and is a part of that ring stuck in a cylinder port? ..... preventing the piston from moving... preventing the crankshaft from moving.. preventing the flywheel from moving..