Conon 500D AF won't work
It is the 18-55mm kit lens that I am referring to.
The faint noise I hear is a two-beat sound -it could very well be the IS working.
IS tends to sounds whirry and sometimes scritchy but not beaty, in my experience.
The switch is definitely on AF.
Can a lens just break without mishandling it?
Yes, that one is renowned for a cable breaking inside that makes it do like you're describing.
Best thing is to find someone who can test your lens on their camera and their lens on your camera. If it is the lens I'd recommend getting the latest STM version rather than repairing that one (though it is possible for a competent person to do so with parts from ebay).
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