IBM H Series Installation And Service Manual page 229

After you have entered and verified the password, the privileged–access password
icon flashes and changes to the locked position to indicate that your computer now
requires the password you just entered before running system programs.
Note: If you forget the power-on password, the battery must be removed for longer
than 30 seconds to reset the NVRAM. Contact your service representative for
assistance.
Chapter 6. System Management Services
6-15