At a device that it is 14+ years old, you should assume it has failed. You can boot to diagnostics and run the SLDIAG tests if you wish, but buying a replacement from ebay is likely the best option.
you can connect to the controller by a serial console and boot the controller. If it can boot sucessuflly, pls. ctrl+c to boot menu and then choise boot to diagnosis. you can find the mother board test etc.