Dell P139G Service Manual page 119

Draining residual flea power, also known as a performing a "hard reset", is also a common troubleshooting step if your computer
does not power on or boot into the operating system.
To drain residual flea power (perform a hard reset)
Steps
1. Turn off your computer.
2. Disconnect the power adapter from your computer.
3. Remove the base cover.
4. Remove the battery.
5. Press and hold the power button for 20 seconds to drain the flea power.
6. Install the battery.
7. Install the base cover.
8. Connect the power adapter to your computer.
9. Turn on your computer.
NOTE: For more information about performing a hard reset, search in the Knowledge Base Resource at
support.
www.dell.com/
Troubleshooting 119