Sounds like you know what you are doing. Sucks you are having trouble.
By this, do you mean you aren’t even hearing the fans on the control unit? You might try opening up the main control unit and look for any obvious loose cables. Maybe it’s something as simple as the power cable not being connected (quick edit: not connected internally).
DavidKSantistevan has some images here of what the insides look like, maybe that can help (it looks pretty messy, though).