Holding the power button to turn off the BlackBerry does not fully turn off power, at least not on the models I've used and the model I use now. I'm not even sure using the "Turn Power Off" icon will completely shut off all circuits from the battery.

My advice if the blackberry is going to be left for weeks is remove the battery; and if for days, put the handset in a charging cradle.
Posted via BlackBerryForums.com Mobile