Though the previous post may have a 65% chance of working, you should warn the user that this could cause further issues if not the problem. Recovery Console, if used incorrectly, can lead to further complications. A corrupt MBR can also lead to a similar issue - Symptoms: Blank screen after POST, Error: Missing Operating System, Error: Error Loading Operating System (malware might be the cause). The user has not given enough info on how far the boot process gets before restarting. They could try your fix but with due care.