On a school trip yesterday my son had his cell phone in his pocket, and also put some really strong hematite magnets the kids call 'sizzlers' in his pocket... since taking the phone out the display turns completely white. He's tried taking the battery out and rubbing the phone against his pantleg then putting the battery back in. (no clue where he got this) and the display comes back after a few tries, but not for long. Usually next time he flips it open it's white again. Is there a way to fix this?

Remove battery and press the power button holding it down for 30 seconds to a minute. Replace battery and turn phone on. The power button is a master reset and it should work. If it doesn't work probably time for a new phone as the damage appears to be too great or take it to a dealer and see if they can fix it.