Doesnt power on or charge

good day!
did you give it 24hrs to finish a charge?
the PC has a charging chip inside.
new battery from whom>?
the line pack is not a charger its line power pack,
it converts 120vac (or 240 outside usa) to 19vdc.(Or your spec)
the 19vdc runs the PC perfectly with no battery installed DOES IT>
that is the first test. the power pack must be the the correct pack
for:
voltage
current (never lower spec)
and watts.
if not the correct power pack it will now work correctly
the watts can be higher no problem,

if it runs ok on line power no battery
then we try the battery. (give it 24hrs for stubborn old batteries)
if the power pack is ok, it will charge, (spec pack as HP tells you)
if the battery is bad it will not.
if the charger chip in the PC is bad (MOBO BAD) then it will not

testing takes, skills and tools, one tool is a voltmeter
lacking that tool, one can only guess.
what not get your PC repaired by a TECH.???????

here is your HP page, its non trivial, no>?
see that they have 5 power packs used
that is BECAUSE they HAVE many power levels of CPU/GPU
faster rated CPU'GPU need more power.

https://support.hp.com/us-en/product/hp-compaq-nx7400-notebook-pc/1847094/how-to

you never once said
it runs perfectly on AC power only
not once
nor it does not overheat. nor if the fan works and vents all are free of lent.

back light problem
check led and inverter

Check Device Manager to see if the wireless driver is installed, if not the download the wireless driver and install it on your HP laptop.
You can download the wireless and device drivers from the Compaq/HP WEBsupport/download page. Make sure you select your model laptop and the Windowsdrivers you require and install them. Click on this link to download thedrivers: -
www.compaq.com/country/cpq_support.html

Try charging it for a few minutes before turning it on. The batteries might be drained.

Hi,
Remove the battery from the portable and disconnect the Ac adapter. Press and Hold down the power button for 15 seconds.

Reconnect the Ac adapter only and power on the system. If the system is doing the same . The motherboard on the computer has gone bad.

You can read more on the same on the link below
HP support forum

Thanks for using Fixya
Proton

Hello!

Im assuming you are asking what the part number or model number of the motherboard is, to answear that it is:

417516-001 - HP Compaq nx7400 Series Laptop Motherboard (System Board)

if you need to buy one, a refurbished one is here, with the current number of them instock at 5.

http://underbid.com/product/461-969/417516-001+MB+N/417516-001_-_HP_Compaq_nx7400_Series_Laptop_Motherboard_System_Board_New.html?ref=base

I hope this has helped you!

Regards
-Jonathan

There is an inverter. Google (nx7400 inverter) for where to buy it.

Do you have another power cord to check? Most places like bestbuy is willing to let you test a universal power cord for your type of laptop before you buy. Usually in your case, the power cord or connector has gone bad. If you test the laptop at the store and it doesnt work then its your connector but if it works. you could consider buying that power cord.

Some laptops will not power up with a completely discharged or faulty battery. Remove the battery from the laptop, plug in the power cord and try to boot the system. If the system boots, your battery needs to be replaced. Replace your battery as soon as you can, it's not a good idea to run the laptop for extended periods with an open battery bay.

pls I need the bluetooth drive for my hp compaq nx7300,thank you