HP 33s - Manual (Page 298)

A–4 Support, Batteries, and Service
Warning
Do not mutilate, puncture, or dispose of batteries
in fire. The batteries can burst or explode,
releasing hazardous chemicals.
5. Insert a new CR2032 lithium battery, making sure that the positive sign (+) is
facing outward. Replace the plate and push it into its original place.
6. Remove and insert the other battery as in step 4~5. Make sure that the positive
sign (+) on each battery is facing outward.
7. Replace the battery compartment cover.
8. Press ‡ .
Testing Calculator Operation
Use the following guidelines to determine if the calculator is working properly. Test
the calculator after every step to see if its operation has been restored. If your
calculator requires service, refer to page A–7.
„ The calculator won't turn on (steps 1–4) or doesn't respond
when you press the keys (steps 1–3):
1. Reset the calculator. Hold down the ‡ key and press . It may be
necessary to repeat these reset keystrokes several times.
2. Erase memory. Press and hold down ‡ , then press and hold down both
 and  . Memory is cleared and the  &  message is
displayed when you release all three keys.
3. Remove the batteries (see "Changing the Batteries") and lightly press a
coin against both battery contacts in the calculator. Replace the batteries
and turn on the calculator. It should display  &  .
4. If the calculator still does not respond to keystrokes, use a thin, pointed
object to press the RESET hole. Stored data usually remain intact.
If these steps fail to restore calculator operation, it requires service.