No displays will turn on

I bought a Sonos 5500, which seemed to work fine initially. The ultrasound tech did 1 study, which worked just fine. He was halfway through a second study when he said that he smelled smoke and the machine stopped working. Currently, when the power switch is activated, the peripherals activate just fine (VHS, Printer, DVR). The main screen and the 2 touch screens do not turn on. If I open the control panel, there is a 4 character LED display that says "BUS ERROR * FAULT ADDRESS = 00926001H PC = 0003ECDCH" I tried looking in the service manual, but I can't find any reference to this LED display or the error codes that it gives. I called the nearest ultrasound repair to me (about 90 minutes away). The had me look at the power supply. The power supply has several green lights, all of which light up when I flip the power switch except for the one labeled +12V. The technician told me that this was the problem and said that he would charge me about $1000 for the replacement part and installation (given the travel distance). I told him no and about a used power supply on eBay. I have installed the new power supply and all of the green lights on it light up, but the LED display under the control board still gives the same error. As background, I did install the DVR myself after receiving the machine. I disconnected the A/V I/O plugs from the VHS and ran them to the DVR, but needed to still power the VHS because only when I have it powered on and use the machine VHS controls to "play" can I see output from the DVR. Both of these devices still seem to be working normally, so I don't think that modification has caused the problem.