Why doesn't my computer start up when I push the power button?

You may want to reseat the power button cable. Remove the screws on the bottom with a PH0 screwdriver, then use a flathead screwdriver to pry off the upper and lower case. Use a spudger to remove and reseat the ribbon cable that connects the power button.

You may have a faulty battery. This could be due to either a hardware or software problem. You can find out by flashing your BIOS. Follow the instructions to update your BIOS. After your computer has restarted test and see if you updated laptop will power on without being plugged in. If not, you may need to purchase a new battery and install in

either the power switch is bad or the battery is not charged and the power supply is bad

wbw

I have dealt with many models of the HP DV4-xxxxxx. When you plug the power adapter into the Laptop you should see a little white led light to the left of the power port where the adapter is. With a battery installed or not this light should be on if the Motherboard is accepting power. If your battery is good you will also see a led light on the left front of the Laptop indicating it is plugged in and charging. If your battery is completely dead but will still take a charge the light will be blinking. It will blink until the battery starts charging and then become steady. If it keeps blinking the battery is bag and will take a charge. Replace the battery or you can remove it and operate the Laptop with just the power adapter. I will post more about this No Boot later.

I too have dealt with a few HP dv4 S if the Caps light light and the scroll light light are blinking it's an indication that you either have a motherboard or CPU failure.