HP Elitebook 820 won't start - blinks 9 times

[Toyito]

My HP elitebook 820 was working very well but this morning it had turned off by itself and when I tried to start it, all it did was blink the front yellow light (bottom left) 9 times and nothing else happened.

I took the battery out and tried to start it using the charger but nada. Still dead. Thanks for your help.

 

[Mark RM]

Is there a pause BETWEEN the blinks? Because , there are no nine blink error codes, thus it may be three blinks three times...
http/h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c01732674