Note: Do not use a Hard Reset except as a last resort such as when both the screen and hard keys are not responding. This is equivalent to turning off a computer by pulling out the power cord instead of shutting it down.
For other options, see
How do I reboot or reset a LabQuest?
Original LabQuest Troubleshooting and FAQs (Full List)

  1. To perform a hard reset, put the stylus on the reset button (see image below).
  2. While looking at the face of the LabQuest, press and hold the reset button for 15 seconds. The blue power light should turn off while you are depressing the reset button.
  3. Release the reset button. The LabQuest should boot normally.

The reset button is located on the back of the unit, to the right and above the battery door, just below the stylus sleeve.

2433-labq_reset_button.jpg

See also
Original LabQuest Battery Troubleshooting and FAQs