While flying along, one of the props on the drone snapped. The whole drone tumbled out of the air and landed on the ground, snapping one of the legs and completely ripping off the sensor array.

I tried using DJI's online repair service but it said my drone was unavailable for repair. I also tried contacting DJI support but it looks like that service is currently down.

Please help, what do I do?

Hi, there. We are sorry to read about the accident. May we know how you contact our support?
And besides,  as the drone got damaged, for flight safety, it is suggested to send the drone to DJI for service.
You can click https://www.dji.com/service/repair to start an online repair case.
If you still meet problems when you start a case, please send us a relevant screenshot as well.