My Compaq Presario F756nr will not turn on. The blue light to the power cord is on and blue light on front of laptop is orange but when you press the power on button it comes on then goes right off.

the WiFi isn't on if it's orange press that key and it will turn blue when it is on..with the battery take it out , count 20 seconds then put it back in and it should work

http://www.compaq.com/country/cpq_support.html

With an extensive use of the notebook,
some times notebook would store some static charges which
indeed will stop the notebook from powering up or charging
the battery. The procedure to remove this static charges from
the notebook is known as power drain. Performing a power
drain procedure will not effect any personal data or delete
any pictures from the hard drive on your notebook.
I recommend you use Power Drain procedure by following these
steps:

1. Disconnect the AC Adapter.
2. Remove the Battery.
3. Hold the Power button down for 30 seconds to 1 minute.
4. Reconnect the AC adapter.
5. Turn on the Notebook power.

1. Check your power cord & adapter.
2. If its working then check the battery, reseat the battery & check.
3. If available then check with another battery.
   If no, then remove the battery & switch on the PC in AC mode.
4. Check if battery charging indication or AC power on indication is glowing. if not then need to change ur motherboard.
5. If indication is OK, but could not power ON then check ur RAM for any loose connection or dust. clean & reinstall.
6. If still no display, connect an external monitor, check if display is coming. If Display is coming then your LCD need to replace.
   
7. Still nothing change, take it to a service centre.

Having the same issue. Did you find a solution yet?

Sometimes when a PC gets stuck in hibernation mode, the only way to reset it is to remove the CMOS battery for 10 minutes and replacing it. It resembles a large watch battery and is usually located near the center of the motherboard.

HI,

POWER ON POWER DOWN PROBLEM,ITS DUE TO AC TO DC INVERTER CIRCUIT IN RIGHT SIDE, INSIDE OF LAPTOP,IT IS SHORTED,APPROACH LAPTOP CHIPLEVEL LEVEL LAB FOR REPAIR.

TNKS

RABBANEES

Sounds like you need a new cmos ( that is a "10yrs" life button-cell battery located on the motherboard needed for the PC to boot ).
Is there a quick flash of a blue screen that says at bottom cmos checksum fail?

1. Remove the battery.

2. Check the power supply connector to make sure that the two prongs at the end are on either side of the pin, as you may not have enough power to fire the machine.