Same problem here with Escient DVDM-300. I focused on the two problem areas that seem to be the most popular in the forum thread, power supply and IDE cable.
First, I opened up the 'boat anchor' and checked the power supply, no visual signs of component degradation or failure.
Second, I powered the unit with the case off and measured the 5V and 12V power supply output to the hard-drive at the connector and found both to be nominal. Next, I measured the 3.3V, 5V and 12V power supply output at the connector to the main controller/mother board and found these to be nominal as well.
Third, I checked the parallel ATA (PATA) cable by performing a pin-to-pin continuity check on all 40 connector pins between the controller/mother board IDE ribbon-cable connector and the master (HDD) IDE ribbon-cable connector, no problems were found. I did not check the continuity at the slave (CD drive) connector because the unit is configured to boot from the hard-drive.
Finally, I powered the unit with the case off and checked to determine if the hard-drive was spinning. I can hear and feel the hard drive running but nonetheless the media manager continues to flash the stand-by LED.
I can't really do much more without a schematic...So I sent an Email to the folks at Escient to see what they have to offer in the way of service/repair advice.
The only other test I think I will try is to remove the hard-drive and connect to a computer to see if I can read from it.