Nissan Repair Questions? Ask a Mechanic for Answers ASAP
I am sorry that you have not been helped yet. I just came online and saw your question
Ok, you dont want to force it as it sounds like the valves are hitting the pistons, or you have a bent valve. If the timing belt broke, then there is likely bent valves due to them hitting the pistons. If it didnt break, then you dont have the timing marks set properly and need to reset them
Ok, at this point to prevent damage to valves by forcing it, you will need to either remove the head and set the cam or loosen the rockers to give valves some play so that turning the cam will not bend the valves.