Some of the terms used by techs and myself:
Means No Power, No Lights, No Charge Light.
Check DC Jack, test with known good battery
No Power/No Lights:
The unit will work from charged battery, but not from AC. Some light may be on.
Check DC Jack.
When you move the charge plug with battery installed, the charge light may come on intermittently. This is caused by a cold solder joint on the DC Jack, or bad contact inside the jack.
No Power/With Lights:
If you hold the plug at an angle, the unit will come on, but letting go of plug it shuts down.
Check DC Jack
Will Not Charge Battery:
Unit runs when plugged in, but will not charge battery. Or the battery only last 15min after charging all day.
Check Adapter - Generic or Wrong Amperage
Example -If you are using a 65w charger and trying to charge a DV9000 the battery will never fill up to it's maximum.
Volts x Amps = Watts 18.5v x 3.47a = 64w and 18.5v x 4.47a = 90w
Posts and starts to run, then reboots.
Suspect CMOS battery
Lights on panel flash when I press the power button:
Suspect dead/near dead battery.
Check DC Jack
Check Charge Adapter
Blue Screen of Death [BSOD]
Very common issue with hardware changes or failure, wrong drivers
Start laptop, continue to press F8 until you get a Start Up Menu
Disable Auto Restart
Restart in Safe Mode - Disable all items in Startup until you take to shop
Or uncheck all unknown/unverified software
You can also remove or disable unused items in System Hardware, modem, network cards and reboot until culprit is found.
Those are just some of the symptoms that you may read on this site.