!!
critical HP
Error Code Power LED blinks red, 9 blinks with a pause
System powers on but is unable to boot.
? What Causes This
Configuration or device issues preventing normal boot process.
✓ How to Fix It
Clear CMOS settings, check setup options and boot order; if not resolved, service may be needed.
Source: page 2 of the official manual
From the manual
This error code appears in:
HP Prodesk 600 G1 Small Form Factor PC