I just bought a used Powershot A590 and it has the same low battery indication even with new batteries. I suspected a contact problem so I cleaned the contacts on top and bottom of the battery case area with a little rubbing alcohol on a Q-tip and let it dry. This seems to fix the problem, however based on what I read here I suspect the problem will recur. I like the solution with the L-shaped dental pick used to bend (pull) up the contacts SLIGHTLY and I will be doing that if the problem recurs. If you get unlucky and break off the contact you may be able to carefully fold a small square of aluminum foil and drop it into the battery hole to make contact with the remaining metal.