System Board Built-In Self-Test (M-Bist); Display Panel Power Rail Built-In Self-Test (L-Bist) - Dell P46E Service Manual

System board built-in self-test (M-BIST)

About this task
Steps
1. Press and hold both the M key and the power button to initiate M-BIST.
2. The battery-status light illuminates in amber when there is a failure with the system board.
3. Replace the system board to fix the issue.
NOTE: The battery status LED will not illuminate if there is no failure present with the system board. If further
troubleshooting is required, proceed with the applicable Guided Resolution for No Power/No POST, etc.

Display panel power rail built-in self-test (L-BIST)

About this task
Next steps
L-BIST (LCD Power Rail Test) is an enhancement to the single LED error code diagnostics and is automatically initiated during POST.
L-BIST isolates if the LCD is receiving power from the system board. L-BIST checks if the system board is supplying power to the LCD by
performing an LCD Power Rail test. If there is no power going to the LCD, the battery status LED flashes a [2,8] LED error code.
92 Troubleshooting