MSA20 Drive won't rebuild

[justb21888]

We have an MSA20 attached to a DL585 G5 via a 6400 array controller. We had a failed drive in the MSA. Since we don't have a maintenance plan any longer on this machine we ordered a drive from HP and I installed it. It appeared to be rebuilding normally but but after about 5 minutes the light went dark on the drive and upon checking the ACU it said "drive queued for rebuilding" We waited over 24 hours and still it hasn't progressed. We then decided to power cycle the server and the MSA20. After the power cycle we recevied the same chain of events. It looks like its rebuilding only to stop a few munutes later. We noticed that the 6400 in the ACU says "cache not configured" and it won't let us configure it either. The ACU errors out and asks for you to close the program. Any thoughts/advice/suggestions? I have tried other 6400 controller cards as well and receive the same errors.