Hieroglyphs would be displayed a few seconds after system failure, and then the electromagnetic force near the concrete wall in the Hatch would begin to build rapidly, pulling any and all magnetic metallic objects inward from increasingly great distances. (Non-ferromagnetic metals, such as copper, aluminium and brass were not visibly affected; this is why Desmond's key was not affected by the force.) The words "System Failure" would repeatedly scroll across the screen of the computer, and the event would be logged on the computer at the Pearl, where a corresponding printout could be produced. There would also be a loud alarm sound, and the speakers would repeat "system failure," with a female voice.
If the electromagnetic force hadn't yet destroyed the computer, there would still be time to enter the numbers and terminate the System Failure, preventing further damage.
At least two system failures are known with certainty to have occurred: