kick yer mate in the nads...them turn your bottom crank...it might be tight cos the piston rings will be dry if u didnt oil the fookers....might be fooked now if it was towed
if u dont want to take the heed back off...take the plugs out and squire a bit of oil in there...try turn the bottom pulley...if its jammed it might be able to be free'd when the heads off...if not ure guffed iut