How can I fix my Sony Cybershot 6.0 - won't turn on?

My Sony Cybershot camera won't turn on. The battery is fully charged, but when I press the power switch it just comes up with 'Access' for a few minutes, then tells me to turn the camera off and on again. It then has problems turning off as the lense won't retract and it takes several attempts of holding the power button down for it to actually retract fully. It's a sony cybershot camera, 6.0 version.