HP 39g+ - Manual (Page 259)

Reference information R-5
To erase all memory and reset defaults
If the calculator does not respond to the above resetting
procedures, you might need to restart it by erasing all of
memory. You will lose everything you have stored. All
factory-default settings are restored.
1. Press and hold the
>21@ key, the first menu key, and the
last menu key simultaneously.
2. Release all keys.
Note: To cancel this process, release only the top-row
keys, then press the third menu key.
If the calculator does not turn on
If the HP 39G/40G does not turn on follow the steps below
until the calculator turns on. You may find that the calculator
turns on before you have completed the procedure. If the
calculator still does not turn on, please contact Customer
Support for further information.
1. Press and hold the
>21@ key for 10 seconds.
2. Press and hold the
>21@ key and the third menu key
simultaneously. Release the third menu key, then release
the
>21@ key.
3. Press and hold the
>21@ key, the first menu key, and the
sixth menu key simultaneously. Release the sixth menu
key, then release the first menu key, and then release the
>21@ key.
4. Locate the small hole in the back of the calculator. Insert
the end of a straightened metal paper clip into the hole as
far as it will go. Hold it there for 1 second, then remove
it. Press the
>21@ key.
5. Remove the batteries (see “Batteries” on page R-7), press
and hold the
>21@ key for 10 seconds, and then put the
batteries back in. Press the
>21@ key.