I wish I had found this thread before. Just had the same symptoms on my several years old x48. I was going to take it up to Dallas to get it fixed, but bought a new x48mkII this week because I have some recording to do. The mkII arrived with the exact same problem ... fails to boot. I guess I'll go look for a battery for this tomorrow and try the bios changes.
The bios on the X48MKII is password protected. It doesn't accept 'admin'. So, I can't even try this fix on the new machine.
well, I did get the old x48 working. Appears the disk drive may have failed. I installed a new one, and with the procedure described was able to get the OS installed and booted. I wonder if the mkII uses that same password suggested in the procedure for the old x48. btw, I installed 2 2TB disk drives, while I was at it. There was a spare sata port, so now I have back-up in the case. Two of the WD Red drives.
well, it turns out they used the same bios password on the mkII as suggested in the older x48 document. They have AHCI option, but have the sata set for IDE, which seems weird. Anyway, mine didn't detect the master disk at all in the bios. I pulled off the case top, and found the power cable unplugged from the drive. So now I have a back-up system and don't have to drive to Dallas.
got up this morning and the old x48 had cmos checksum error. It restored defaults which don't work. So replaced the cmos battery ... it was cr2032 3V, as you said. I set up the bios again, and now it boots ok again. Battery holder just had a little metal clamp on one side that you push aside. I used some needle nose pliers to hold it open. Used a magnet to lift out the battery since it is kind of tight spaces.
Tested the drive recording speed ... good for something like 150 channels at 96khz ... so no problem there. The second internal drive speed not testable with their software. I will just use it as backup.