If it's hydrolocked, the motor will spin freely without the plugs installed. Fix the problem and then turn the motor over a few times.
Suspect causes would be the o rings between the blower and LIM, the blower gasket, or the lim gaskets. If the blower was ever off the motor then that would explain it maybe. Also it needs to be bled decently after the coolant system is closed, or you will get air pockets and heat.
If it has been run without enough coolant or oil though, then it could be seized due to heat. That's solvable too, as long as the problem has been corrected......
Suspect causes would be the o rings between the blower and LIM, the blower gasket, or the lim gaskets. If the blower was ever off the motor then that would explain it maybe. Also it needs to be bled decently after the coolant system is closed, or you will get air pockets and heat.
If it has been run without enough coolant or oil though, then it could be seized due to heat. That's solvable too, as long as the problem has been corrected......