Have you got a set of known good SIMMs on board? :?:

Are they the type that you put in PCs or Macs?

If they haven't been verified as yet, do you have another system in which you can test them?

It sounds like a failure right about the time the Rocket tries to start functioning . . .

. . . so a RAM Check could be the hang-up . . .

. . . dunno . . . just trying to cover all the basic troubleshooting steps as they come to mind . . . :-/