I have an HP ProBook 4520s that will not boot.
It has the orange light blinking above the port for the power supply.
When you plug the power supply in it turns white for 1 blink then orange again.
I have read on multiple sites that you can take the battery out, hold down the power button for a length of time, say 20 seconds, plug in the power supply and viola, it works. Well, it doesn't work on this one. I just get the blinking. Maybe I am just going about the process wrong. I consider myself somewhat computer savvy but different perspective sometimes helps.
I have not tried a new battery. The posts all say it is not a battery issue. I found plenty of posts on other sites when I Googled it but have always had good luck here. Thank you in advance.