Piston will not push valves shut, they only bend them! Get valve train in time or completely loose ( pull the rocker arms ) before proceeding with any rotating.
If this has sat for a summer or longer, its really not hard to believe it has rusted a bit, and pretty sure it's humid where you live.
Really no chance of harming the crank while beating the balancer back on. You didn't use a 10 lb sledgehammer did you?
