If the calculator has two batteries this is normal and not indicative of any problems with the unit. To perform the self test on units with two batteries:
-
Turn the calculator off.
-
Press and hold the
and 
keys; keep both keys held down for the next step. -
Press the
key so the 
and keys are held down simultaneously. -
Release the key.
-
Release the key, followed by the key. The main test screen displays the following: '1.L 2.C 3.H'.
-
Press
to perform the LCD test (all LCD segments will be turned on). Press any key to exit. -
Press
to perform the checksum test and see the copyright messages. Press any key to go from one screen to the next until the main test screen, '1.L 2.C 3.H', is displayed again. -
Press
to perform the keyboard test. Press EVERY key on the keyboard until all the keys have been pressed at least once. The screen will progressively turn off with each key press. Once all the keys have been pressed and the screen is clear, press any key to return to the test screen.
-
Press to exit the test system. This will also turn the calculator off.
to exit the test system. This will also turn the calculator off.If the calculator detects an error at any point, it will display an error message.
For the HP 12c financial calculators with one battery, to perform the LCD self test:
-
Turn the calculator off.
-
Press and hold the
key, and simultaneously press and hold the key. -
Release then .
-
After a few moments, all elements of the screen should be displayed. Press any key to exit.