As soon as I switch camera on it switches off. Batteries are good.

A flashing green light can mean it has problems accessing the memory card.
Check the card is not Locked and if all con acts are clean and shiny.
Never use zinc carbon batteries, not even new ones, because they can't give enough power. The best are NiMH rechargeable batteries of a camera.
Contacts can be cleaned with a dry cloth or cotton swabs. Never use sharp toosl in or close to a camera.

Are you sure your battery (ies) are fully charged? Never use manganese (Zinc-Carbon) batteries, or NiCD rechargeable batteries.
If you have a multi meter, you can check the battery, by measuring the voltage. This should be only a little above the voltage printed on the battery. If it is only a but under the printed voltage, the voltage will drop as soon as you switch on the camera. The cmaer won't work.

You know when you take off teh batteries the camera is switched off too. But if your camera comes on as soon as you replace the batteries, I think your on / off switch must be jammed. Or perhaps something els could cause a shortage in the camera, doing tehsame as pressing the on switch.

I would call Sony and see if they have yur device under warranty still I believe it needs to be replaced

What kind of camera do you have?

Short in the camera so you do not get proper switch off even when you switch the camera off ( so it stays on all the time ). Or your charger is not fully charging your batteries which then go into your camera say half charged and dont last very long.

It's the type of battery you are using. Use a rechargable battery or a long-life disposable rated for digital cameras. Regular (cheap) AA batteries don't have enough power to run this type of device - even if they are brand new. Save the cheap batteries for your wall clock.

rechargeable batteries voltage actually are lower than normal batteries, but is high when freshly charged or still hot after charging. don't use newly charged or hot battery, wait at least five minutes or let the batt cools down first. some model and brand uses compatible rechargeable batt, it is different from those sold individually which i think you are using. it has special switch activator attachment have you tried to switch back to alkaline? how about formatting the card in pc? try removing then reinserting the card for several times. this will clean the card contact point in camera.

there are some power supply circuitry inside, one of those electronic chips maybe damaged.let it be service by qualified tech. Fred Loja

I read Something Similuar where This Individual Recharged The Batteries And Then Somehow Rebooted His Comp And The Camera Then began To Respond?