Hi,
Try a full power refresh and check if that resolves the problem.
Here’s the procedure:
Disconnect the charger from the laptop.
Remove the main battery from the laptop.
Disconnect the RTC coin cell battery from the motherboard.
Here’s the [http://h10032.www1.hp.com/ctg/Manual/c05228980.pdf|maintenance and service guide] for the laptop. Go to p.29 & p.37 to view the necessary pre-requisite steps and then the procedure to remove the main battery and the RTC battery, respectively.
''Press and hold'' the laptop’s Power On button for a ''full 30 seconds'' and then release it.
Reconnect the RTC coin cell battery, re-assemble the laptop, re-insert the main battery, connect the charger to the laptop and try to start it.
If it starts, there may be a message about the date and time being incorrect. This is normal as the above procedure has reset the BIOS back to its factory defaults. Once the date and time have been adjusted, the message won't appear the next time the laptop is started. Any user defined BIOS settings that have been altered by you to suit your particular requirements will need to be changed back also.