locked up 84 regal

hey all a friend of mine wants to find out the socket size to go on the harmonic balancer in his regal to attempt to rotate the motor over that is locked up supposedly with no sign of probs no noises or overheating

Have a 03 Buick Regal, won't start...the security idiot light was flashing before car would not start...according to owner's manual may have tripped security system, any one out there have similar problem or any advice on what I look for to fix problem, don't know enough to even begin fixing problem....thanks for your time