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Error 30 relates to a shutter malfunction.
Shutter problems are delicate and involve a delicate mechanism. There is not much one can do about such a problem, aside from trying to reset the camera, or give it a bit of power-down-rest time - as you have already done.
And of course, sending the camera in for repair. Disassembly of the delicate shutter mechanism is done by expert camera repair-persons at Canon, with the proper tools and lots of practice and knowledge of what to do about various shutter mechanism malfunctions. Canon repair is by and large fairly highly rated for turnaround time etc.
Canon Repair can be engaged through:
or by calling 1-800-OK-CANON. If your camera is fairly new (less than a year old, usually) then the repair would be covered by warranty.