!!
critical HP
Error Code Red LED flashes once and white LED remains on
Embedded controller cannot find valid firmware, system board replacement is needed.
? What Causes This
Firmware corruption or failure to initialize properly.
✓ How to Fix It
Replace the system board.
Source: page 76 of the official manual
From the manual
This error code appears in:
HP Elitebook 840 G6 Notebook PC