HP 10B - Manual (Page 124)

The calculator doesn’t respond to keystrokes (nothing
happens when you press the keys):
Reset the calculator (sec step 1 above).
2 . Erase memory (sec step 2 above).
3« ir the calculator fails to respond after steps 1 and 2, remove the
batteries (page 119) and lightly press a coin against both calcu­
lator battery contacts. Put the batteries back in and turn on the
calculator. It should display ALL CLr.
If steps 1 through 3 fail to restore calculator function^ the calculator
requires service.
The calculator responds to keystrokes but you suspect
that it is malfunctioning:
1. Do the self-test (described below). If the calculator fails the .self
test, it requires service.
2. If the calculator passes the self-test, it is likely that you’ve made
a mistake in operating the calculator. Try rereading portions of
the manual, and check “Answers to Common Questions” on
page 116.
3. Contact the Calculator Support department. The address and
phone number are listed on the inside back cover.
Confirming Calculator Operation
Test
the Self-
If the display can be turned on, but it appears that the calculator is not
operating properly, you can do a diagnostic self-test. To run the self-test:
1.
First, hold down the (C) key, then press iPMTl at the same time.
2. Press any key four times, and watch the display as various patterns
are displayed. After pressing the key four times, the calculator
displays the copyright message COPr. HP 1987 momentarily, and
then the message 01. This indicates the calculator is ready for the
key test.
A: Assistance, Dattarios, and Service 121