Posts: 25
Threads: 2
Joined: Jan 1970
I can only speculate as to the actual reasons (electrostatic discharge risk?), but I would leave the batteries in, if only because HP said so. The following is taken directly an appendix from my old manual for the HP-15C (the 12C manual also says the same thing):
"If the calculator still does not respond to keystrokes, leave the batteries in the compartment and short the battery terminals together. (The batteries must remain in place to prevent possible internal damage to the calculator.) With a paper clip or piece of wire, briefly connect the terminals. Only momentary contact is required. The terminals are matching metal strips, or a combination of one spring and one hard edged tab located at either end of the battery compartment. After you do this, the contents of Continuous Memory will be lost, and you may need to press the ON key more than once to turn the calculator back on."