Symptoms
A Latitude may display a red, green, blue (RGB) screen, and then stop responding with a black screen. The diagnostic LEDs show 3-Amber 6-White. The computer cannot be recovered by performing a hard restart. The BIOS version is 1.1.1.
Affected Products:
Latitude 5420Latitude 7320Latitude 7420Latitude 7520Latitude 9520
Cause
MBIST's code process triggers the recovery process.
Resolution
The BIOS must be updated to a newer version. Reference the following steps to update the BIOS to version 1.3.12 (or newer) and manually recover the BIOS.
Note: For more information about BIOS recovery, reference How to Recover the BIOS on a Dell Computer or Tablet.
To recover and update the BIOS:
Press and hold the power button on the computer for 4 seconds until the computer shuts down.Download the latest BIOS (version 1.3.12 or newer) from https://www.dell.com/support.Rename the file to "BIOS_IMG.rcv" and copy it to a USB drive or SSD.Insert the USB disk or SSD into the computer.Press and hold the ESC and CTRL keys, then plug the AC adapter into the computer (Figure 1). (Figure 1. Plug in the AC while pressing the ESC and CTRL keys)Select Recover the BIOS (using the currently-flashed BIOS) (Figure 2). (Figure 2. Selecting Recover the BIOS)Press OK to start recovering the BIOS (Figure 3). This also updates the computer's BIOS version. (Figure 3. Pressing OK to start recovering the BIOS)The computer boots into the operating system once the process is complete.
