So my 71B, which has been working faithfully for the last three years (on the same batteries!) recently had it's batteries 'liberated' when no other AAA's could be found around the house. A month later I replace them (with bog-standard alkaline AAA's from Ikea) and it's not happy.
The display has every element turned on, and it won't respond to any key presses. Anyone know what's wrong with it, or what I can do?