2012 Mac Pro whitescreen when turned on
I recent received a 2012 Mac Pro system. It was filthy, but working. Last night I disassembled the system and used canned compressed air to blow out the crud from inside the system. I reassembled the system and it was working fine.
This morning I powered up the system and I just get a white screen and a chime. Sometimes the tail end of the chime will repeat at about one second intervals.
I've tried holding SHIFT to get to safe mode, holding the power button for 10+ seconds, pressing the PRAM reset button on the mainboard, replacing the PRAM battery, reseating the video card and reseating the CPU card, but no change.
I notice that there is a DIAG LED button, but not sure what to expect when pressed.
Specs are dual Xeon 6 core processors, 48 GB of memory, 512 GB SSD drive, nVidia GTX 680 video card.
Any idea what I can do from here?
Mac Pro