That is one of the older Canon digital cameras - year 2000.
The light you mention is called the "access" light which is an indication that the camera is writing/reading to/from the memory card.
Right after you insert the card, the light should blink quickly and go out. The camera is reading the card.
If the light comes-on and stays-on, sounds like it can not read the card.
Try another compact flash card and see what happens.
If the new card works OK, your original card can not be read by the camera.
Since you previously had the card in your computer card reader, it is possible the computer wrote something on the card that the camera does not like, or something happened when you inserted the card in the camera.
The only way to recover the bad memory card is to put it back in the computer and delete every file and folder that you can find.
Then put the card back in the camera and the camera should react normally and should turn-on.
Of course, then you need to format the card with the CAMERA.
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I was taking pictures one day when I noticed that the batteries were low so I took it out to charge it. At the same time I took out the memory card so that I can upload my pictures to my laptop. When I placed the newly charged batteries and memory card back into the camera I noticed a red light on the side where the memory card slot is. The red light will not turn off and the camera will not turn on. When I take the memory card out the red light goes off, but the camera still will not turn on. I'm devastated. What can I do?
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