Disk accessing icon flashing is normal... it only means you have disk activity. This may or may not mean a failing HDD.
But if you do not have a screen, not even for BIOS setup or a splash screen during startup in both LCD and/or external monitor.. that's the problem.
For all intents and purposes, I would go with checking if there is screen or not. If you can get screen then go ahead and check for HDD problems. It would almost be next to impossible to check for HDD problems first without a good screen
