I have seen this issue a few times now while performing a disaster recovery of a Backup Exec 3600 appliance. There are many DR scenarios for a Backup Exec 3600 appliance but the one I am referencing in this post is when the appliance is a total loss and you need to move your four data drives from the old appliance to a new appliance.
I have seen some instances that after you move the 4 existing data drives from the old appliance to the new appliance, you get past the Symantec POST screen only to be left at a white cursor that is blinking in the top-left of a black screen.
To give a little background on the appliance there are two hard drive controllers and two logical arrays. The first controller contains a RAID 1 logical array. This RAID 1 mirror contains two 80GB solid-state drives. This is where the operating system resides. These drives are also internal.
The second controller contains a RAID 5 logical array. This RAID 5 stripe set (with parity) contains four 2TB drives and is where your deduplication folder resides. Your Backup Exec catalogs, database and job logs are also stored on this RAID 5 array.
What I have seen happen is that when you transplant these 4 data drives from one appliance to the other is that some times the boot order of the array controllers flips. Basically the BIOS attempts to boot to the hard drive controller that contains the data drives and not the OS drives.
The fix is simple. During POST, when you see the Symantec logo, go into SETUP (BIOS) and change the boot order of the hard drive controllers. Make sure the operating system controller is set to boot first. Saved and reboot. The appliance will now boot to the operating system array and you can continue your DR process.