Why my camera shuts off?

Why my camera shuts off?

I have had my Canon PowerShot SX110 IS for a while now, but now it will power on briefly and then a Low Battery icon comes on, following which it will promptly shut off. The battery door locks & unlocks without problems, the batteries are fresh but I have replaced them again anyway - the results are the same. The battery terminals have been cleaned. I am dumbfounded and can't figure out why.