!!
critical HP

Error Code PWR LED flashing red

Indicates error detected by system hardware.

? What Causes This

Internal issues with hardware components like memory, processor, or PSU.

How to Fix It

  1. Refer to POST error messages and LEDs in manual (Chapter 7).
  2. Disconnect power and unplug peripherals for at least 30 seconds.
  3. Retry boot-up process.

Source: page 84 of the official manual

From the manual

Manual page 84 — HP error PWR LED flashing red

This error code appears in:

HP Elitedesk 800 G2 Small Form Factor PC