critical HP

Error Code Red LED 9 blinks every second followed by a 2 second pause

System power on process results in an inability to boot due to various causes that prevent startup.

? What Causes This

This can be from critical issues such as incompatible BIOS settings, damaged firmware or hardware failures leading to inability of OS loading properly. Can also result when disk drive/controller is unable to initialize itself pre-boot.

✓ How to Fix It

Re-set CMOS via clearing NVRAM and resetting BIOS defaults.
Attempt to reconfigure boot order from within the BIOS setup menu.
If necessary, replace faulty hardware or seek specialized technical support for further diagnostics.

Source: page 4 of the official manual

From the manual

Manual page 4 — HP error Red LED 9 blinks every second followed by a 2 second pause

This error code appears in:

HP Elitedesk 800 G1 Small Form Factor PC