Dell Latitude 5480 Owner's Manual

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M-BIST

M-BIST (Built In Self-Test) is the system board's built-in self-test diagnostics tool that improves the diagnostics accuracy of system board embedded controller (EC) failures.

NOTE M-BIST can be manually initiated before POST (Power On Self Test).

How to run M-BIST

NOTE M-BIST must be initiated on the system from a power-off state either connected to AC power or with battery only.

Press and hold both the M key on the keyboard and the power button to initiate M-BIST.
With both the M key and the power button held down, the battery indicator LED may exhibit two states:
1. OFF: No fault detected with the system board
2. AMBER: Indicates a problem with the system board

If there is a failure with the system board, the battery status LED will flash one of the following error codes for 30 seconds:

Table 1. LED error codesLED error codes
Blinking Pattern		Possible Problem
Amber	White	Possible Problem
2	1	CPU Failure
2	8	LCD Power Rail Failure
1	1	TPM Detection Failure
2	4	Unrecoverable SPI Failure

If there is no failure with the system board, the LCD will cycle through the solid color screens described in the LCD-BIST section for 30 seconds and then power off.