"New" Dell PowerEdge R710 fails to post

I have just acquired a Dell PowerEdge R710. I have attached a monitor, a keyboard, and a couple power cords and attempting to boot. I was expecting to at least see something show up on the monitor, like a message about the BIOS or something, but nothing appears to happen except the fans spinning up. On the tiny little LCD screen on the front, I see "ST: DTDTLM1" on the display. None of the little buttons around the display do anything. I'm kind of at a loss as to where to start. I have looked inside. In one of the slots, there is a riser for the RAID controller card. Everything appears to be well seated.There are twelve 4GB memory modules in A1-A6 and B1-B6, so that should be 48 GB RAM. There are two E5530 CPU's (I'm told, I have not removed the heat sinks). I have been told that this worked fine when it was taken out of service a month ago. I'm hoping I didn't just inherit a boat anchor, as I have a use for this machine if I can get it up and running. I do see several different LED indicator lights lit on the main board and on the RAID controller card, for whatever that is worth.