If you are using NiMH rechargeable batteries, it is possible that one of the batteries is defective.
If you have access to a volt meter.
Check the voltage on each battery.
It should read 1.2 volts (each).
If you don't have a volt meter.
Buy 4 new Alkaline batteries.
If the camera works with the alkaline batteries, it is likely that you have a bad NiMH battery.
Buy a new set of NiMH batteries.
The batteries are fully charged, and playback (view) features work fine, but when we try to turn on camera to take pictures, the screen reads ''change the batteries'' and the lens does not extend.
Cannon tech folks have suggested removing the SD card and batteries for 20 mins, and then trying again. We tried this and still no go. They want us to send it in. We need the camera for an upcoming event and may not get it back in time.
Does anyone have any other suggestions?