There are a few things to check first off.. Verify you are getting 19V from the adapter. Weve ran into this simple problem a few times where the adapter fails, Laptop runs until the battery's depleted, Then it wont start. These notebooks also have DC connector problems with the solder joints.. (As well as all notbooks).. Its not a complicated repair but does require soldering ability and the disassembly of the laptop. Compaq 2100/2500, And the twin HP models also have a solder joint issue where they will not boot from the power buton. They will however boot from the Question mark button on the same power bar.. ( Diagnostics start) If this is the issue with yours its also easily repaired. We can look at it free of charge if you arent able to disassemble or repair. You should invest in a cheap Digital Volt/Ohm Meter with Diode test to check things if you need more assistance. Our ratio on repairs is around 98%.. Its hard to help a customer save money by changing a motherboard. By far better off to change the failed component or components and go from there. If you need help just yell..
www.ikenfixit.com
My Pavilion ze4400 laptop has failed.
The notebook is completely dead-- there is no power light, the LED showing the power cord is plugged in does not come on. No other lights or beeps or anything. I tried the reset button on the bottom, pulled and reinstalled the battery--no response.
I find it strange that it would fail suddenly with no warnings, it was working fine one day, dead the next. Are there any known problems with this series of laptops? Could this be the power supply or motherboard? I don't know where to look first!
BTW, It is 3 weeks out of warranty.
Thank for any help,
jay

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic