Anti-theft lockdown

I own a mechanic shop and I got two cases of anti-theft lockdown I need help with.

1st. Changed instrument cluster in a 00 V6 mustang, as soon as I put the new one in the anti-theft locked down. all the motor will do is spin over and will not start. Any Ideas?

2nd. This is in one of my cars, I put a 98' Cobra Motor in my 97' GT and since the wiring harness was different I swapped it and put in a Cobra instrument cluster then when I went to crank it the anti-theft light went to flashing and all the motor will do is spin over. The motor does run. My buddy wrecked the cobra and sold me the whole car for $300.00. I actually cranked the motor up before I even took it out. Any Ideas to help me with this would be appreciated.