Blinking white amber light above power cord

Take everything out of it that you can. That would mean the ram and drives, see if it boots. IF it does, then put the ram back and check it again. If it does put the hard drive back etc. If you get to the point that it wont boot with nothing installed then it could be a dead cmos battery or a loose CPU or something like that or a bad mother board.

From Hp the blinking light indicates sleeping mode. Suggest you push the power button for 20 to 30 seconds. The light should go out. Repower on the computer. If it goes back to blinking mode then there is a hardware issue.

This indicates one of the following:
1. Dead Battery
2. Incompatible Charger
3. Incompatible battery
4. Static Charge Overload - Take out battery, unplug charger, hold power button for 30 seconds, put battery back in, plug in charger and press power.

LB

sounds like you may have over heated mother board you can try to reseat the cpu if that does not help then it is probably a mother board issue

Try downloading or purchase a Restore CD for your model HP Probook from the HP WEB site. Boot up with this Restore CD and follow the instructions.
http://welcome.hp.com/country/au/en/cs/support.html

When you plug in the power cord is there any lights whatsoever on the laptop, where the plug goes in or on the AC Adapter of the power cord?

When you press the power button do you hear fans running, hard drive spinning, lights on the computer, hear any beeps or lights constantly blinking, hear the DvD/CD drive click and the light on the drawer of the DvD/CD turn on for a second or two? If so the laptop is trying to boot or may have booted, but the screen is not showing for some reason.

Beep tones and blinking lights tells the technicians what is going on with the laptop and why it is not booting. Most times it's a motherboard issue when you hear beeps or blinking lights continuous. Most times the problem is with the memory or Video Card. Count the Blinking Lights or Beeps and take note of their pattern (1 Long or 1 Long followed by 2 Short).

Maybe your power cord is bad if you don't get anything to happen whatsoever when you press the power button. And if that's true maybe you was operating off the battery the last time you had it on and since the power cord is bad, it was not charging the battery so the battery is drained and the power cord is bad.

Maybe you have a Static Charge Buildup. Remove the Power Cord, Remove the Battery, then Press and Hold the power button for 30 seconds. After 30 seconds plug the power cord back in (leave the battery out) and hit the power button to see if it boots. If it does, you can put the battery back in and let it charge.

Maybe your DC Power Jack which is where the power cord plugs into the computer is bad. Take an ink pen and push the tip inside the jack and see if the little pin wiggles, if so the jack is bad. You'll have to take the laptop apart to fix it. Most times it is soldered onto the motherboard, so you will have to desolder the old and solder a new one.

Maybe your memory is bad or the memory slot is bad.

Remove the Power Cord, Remove the Battery, Remove the cover that houses the memory on the bottom of the laptop then remove one of the memory chips. Set the chip aside then try rebooting the computer. If it boots, then you know the memory chip you set aside is bad so mark an x on it with an ink pen. If it fails to boot then move the chip to the next memory slot and try rebooting. If it fails take the chip out and set it aside, then put the other chip in and try booting it in both slots. If it boots, just to verify that the chip set aside is bad, mark an x on it and put it into the open memory chip slot and try booting.

When you insert the battery? What about when you plug the power cord in?

From the descrition this is a motherboard problem, Hp is well known for issues of this sort. Hook a spare monitor to the video output usually on the back, if picture okay! there is a problem with the new screen. But if both show the same symptoms it is the Video Graphics Card normally built into the motherboard. If that is the case a motherboard replacement will be expensive.

Sub out the ram one at a time, if luck is there unit will start, second option is remove the main battery often loads the system down.

Either your charger is not providing the perfect voltage or there is a short circuit in your motherboard. Try replacing the charger first. If still the problem persists then you should check the connector. try resoldering it cause loose connection in it also sometimes causes this problem.or you need to change the motherboard finally.