Need help! Shower enclosure leaking. (Not a plumbing issue.)

My guess it that glass is not sealed to aluminum frame. I would try using something like a sprinkling can and pour water only on glass surface, and see if it leaks. If it does, could try and seal between glass and frame, or take frame apart and reseal glass to frame with new rubber seal, or some good waterproof caulking. Then reassemble and test. Also once you have frame apart, you should be able to see presence of water in frame from leak.