None of your siblings have an alarm you could borrow? Or have to wake up for school as well.
If you there's no other way you could probably consider staying up. It's already 4am, isn't it? Not generally recommended, but better than missing school, I'd have thought.
Do you have your computer on you?
I kinda murdered my alarm clock, and to wake up I had to set my computer to wake me up. It worked like a charm, and then I fixed my alarm clock so it was all good.