4MOT/1/40000003: HDD error message after replacing hdd

had issues with 20 inch imac (4MOT/1/40000003: HDD).Issues started when friends child managed to turn of power surger unit to imac, seemed to kill off hdd so replaced it with new, after various startup issues. hdd now replaced but still giving very occassional annoying power down issues and same error message, very worried that it may be logic board problem( expensive). any relevant help would be welcomed with relish. thanx. Also when i had imac open i noticed a scorch mark on the foil inside unit ;which i suspect has been present since the imac was 2months old as the plastic screen protector also has the same discoloration pattern on the outside, told by apple reseller it was condensation at the time of previous replacement of failed optical drive. anybody out there had any similar issues?