I put 2 good AA batteries in it. It had about 15 MINUTES before it said battery low! So I take the batteries out and I use my battery tester to test the power on them. THEY WERE BOTH FULL! And yet my camera still says they are DEAD! What is going on here?!

You should use rechargeable batteries with digital cameras, these keep the right voltage level the longest. Cameras are considered "high drain" devices. I think that if you put the batteries back in, the low battery light will not come on right away since the battery would have recovered somewhat.