How do I interpret blink or beep codes on the HP Z240 Tower Workstation?

If you see flashing LEDs on the front of the computer or hear beeps, you should refer to the Maintenance and Service Guide (English only) for interpretation and recommended action. These blink and beep codes are POST diagnostic signals that help identify hardware issues. The Maintenance and Service Guide is available at http://www.hp.com/support/workstation_manuals. (Page 26)