I sincerely hope you can appeal because that is a load of shit and I refuse to believe they can't reschedule an online exam. I mean, you can't be the only student in history who suffered a power failure, you know? But shit man, I feel awful for what happened. You need to vent/ plan a murder hit me up.

In the mean time, change your sister's Facebook password and recovery e-mail and then apply to have the account deleted. That should be suitable revenge on the idiot.