HP Pro 2110 Small Form Factor Maintenance & Service Manual page 158

Computer appears locked up and will not turn off when the power button is pressed.
Cause
Software control of the power switch is not functional.
Computer shuts down automatically.
Cause
Thermal protection has been activated.
Computer will not respond to USB keyboard or mouse.
Cause
Computer is in standby mode.
Computer date and time display is incorrect.
Cause
RTC (real-time clock) battery may need to be replaced.
NOTE: Connecting the computer to a live AC outlet
prolongs the life of the RTC battery.
148 Chapter 9 Troubleshooting Without Diagnostics
Solution
1. Press and hold the power button for at least five seconds
until the computer turns off.
2. Disconnect the power cord from the electrical outlet.
Solution
1.
The computer might be in an exceedingly hot
environment. Let it cool down.
2. Clean the air vents on the front, back, or any other
vented side of the computer.
3.
Ensure that there is a 10.2 cm (4 in) clearance on all
vented sides of the computer to permit the required
airflow.
4. Ensure that computers are not stacked on top of each
other or so near each other that they are subject to each
other's re-circulated or preheated air.
5.
If the computer is within an enclosure, ensure that there is
proper intake and exhaust ventilation for the enclosure.
6.
If a message appears on the screen indicating that a fan
is not working, replace the fan.
Solution
To resume from standby mode, press the power button or
press any key.
CAUTION: When attempting to resume from standby
mode, do not hold down the power button for more than four
seconds. Otherwise, the computer will shut down and you will
lose any unsaved data.
Solution
First, reset the date and time under Control Panel
(Computer Setup can also be used to update the RTC date
and time). If the problem persists, replace the RTC battery.