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I edited your post as it broke rule #5 (read here:
http://forum.thinkpads.com/viewtopic.php?f=16&t=14339).
The I9990xxx error codes means that the system did not find a bootable hard drive. I9990302 is "invalid hard disk boot" and I9990305 is "no bootable device". The Hardware Maintenance Manual says to do the following:
- Reseat the boot device (disconnect it from the systemboard and then re-connect it)
- Check the startup sequence for the correct boot device (verify that the boot order in BIOS has HDD-1 listed)
- Check that the operating system has no failure and is installed correctly (usual method would be to install the hard drive in another system that is known to work)
Since you did the first item, I would check to see if the hard drive is one of the devices in the boot sequence. Power up the system, press and hold the F1 key to access the BIOS. I believe it is called "Easy-Setup" in the 760 systems. I do not have a 760 but this works on a 600: Click on the Start Up icon, then Power-on. You should see a list of device icons at the top, 1-4. This is the boot order for looking for a bootable operating system. Most people will have the floppy (FDD), CDROM and then hard drive (HDD-1). If you need to change the devices or the order, use the Reset icon at the right. That will clear the boot order line. Then click on each device in the order you want. Click OK to save.
The errors you see in the diagnostic menu (DEV/ERR/FRU) means that the BIOS has found a problem with the hard drive or the hard drive controller on the motherboard.
I would guess, given the age of the system, that the hard drive has failed. So, yes, it is probably time to find a suitable hard drive. You would have the best luck if you keep the size of the hard drive under 2GB as that was the biggest drive offered in the 760 systems. Unless somebody here in the forum can say that the 760EL's BIOS can handle larger drives.