My daughter's Blackberry phone works fine when the charger is plugged in but as soon as it's disconnected, it goes dead. I have checked the battery which is fully charged with a multimeter and it is 4.1V which is fine. Has anyone any ideas please?
Have you tried turning it off and back on again?
My son's had a similar problem a couple of weeks ago. I got it working by jiggling a small screwdriver in the charger hole.
As the redoubtable Mrs O says, the most likely thing is that something has got stuck in the 'charger hole' (lovely turn of phrase that) which is preventing the BlackBerry switching back to battery power when the plug is removed. Investigate gently ...
Failing that, I suggest you pop down to a local phone store and see if they will kindly try a spare battery if they have one, if only to be certain that it is not your battery that is at fault.