Could be a bad;
1) AC adapter (Charger),
2) DC Power Jack, (Jack that the AC adapter plugs into on the laptop),
3) Power On switch, (Power Button Board),
4) Display Lid Switch Module,
5) Power MOSFETs on the motherboard,
6) Ceramic Capacitors on the motherboard.
1) AC adapter:
The plug end that plugs into the laptop has a Center Hole, and a cylindrical metal outside shell.
The center hole is the Positive connection.
The cylindrical metal shell on the outside is the Negative connection.
Multimeter function knob set to DC Voltage, the Positive (Red) probe lead goes to the Center Hole.
The Negative (Black) probe lead touches the cylindrical metal shell.
[An inexpensive multimeter can be purchased for as little as $5 to $12. Available in a multitude of stores. An auto parts store is but one example, or look on the checkout aisle racks of major discount stores.
If just a symbol, the symbol for DC Voltage is a dotted line over a solid line. More expensive multimeters have an auto detect feature, that sense when the multimeter is connected to AC voltage, or DC voltage )
You should read 18.5 Volts (DC)
While testing have an assistant gently wiggle the cable from AC adapter to laptop, and the power cord to the AC adapter. A fluctuation of the reading indicates there are broken wires.
AC adapter checks out OK?
Go to the DC Power Jack.
The DC Power Jack on the laptop may have DC_IN next to it.
It has a Center Pin, and surrounding metal shell.
Battery REMOVED, use a No.2 pencil, and see with the easer if you can move the center pin.
If so the jack needs to be replaced.
The DC Power Jack for this model series is attached to wires, that end in a small white plug.
The small white plug plugs into the motherboard.
Easier to replace, than models that have the DC Power jack soldered directly, to the motherboard.
It's a DC Power Harness, and HP labels it a Power Connector Cable.
HP 430462-001 for models that have a UMA motherboard.
HP 430461-001 for models using an Intel processor.
DC Power Jack checks out OK?
Power On switch.
In the list click on -
HP Pavilion dv2000 Notebook PC Maintenance and Service Guide
This is a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.
After you click on the above file name, it may take up to 30 seconds before the first page comes up.
The PDF reader page numbers, and the actual manual page numbers, do not match. When I refer to a page it is the PDF file page.
Go to Page 141 - Switch Cover
Pages 142 and 144 have more details on the Power Button Board.
(Power Button Board is HP part number 417084-001)
How to test?
Multimeter set to OHM. Straight pins (2) in the socket holes of the removed, Power Button Board's cable connector.
Positive probe lead to one pin, Negative probe lead to the other straight pin.
Press the Power On button.
ANY reading indicates a good Power On switch.
No reading of course means a bad one.
(Remember; the Power On switch is a Momentary Contact Switch.
You will just get a brief reading on the multimeter, if good)
Or you can use a small flat tip Jewelers screwdriver, and TEMPORARILY touch the two contact pins on the motherboard, where the Power Button Board's cable plugs into.
Page 179 for the Display Switch Lid Module,
Unplugging the Display Switch Lid Module from the motherboard, and pressing the Power On button, starts the laptop, you need a new lid module.
Power Button Board, (Power On switch), and Display Switch Lid Module checks OK?
There are Power MOSFETs on the motherboard. These are located close to where the plug of the Power Connector Cable, plugs into the motherboard. (DC Power Harness)
The Power MOSFETs control;
Whether the Battery needs a full charge, or a trickle charge.
Whether the laptop is to just run off of the AC adapter, or Battery.
Look to see if any are blackened, burned, or blistered.
Information using the HP Pavilion dv6000, and Pavilion dv9000 series of Notebook PC's,http://mayohardware.blogspot.com/2010/04/important-parts-on-dv6000-and-dv9000.html
Just to show the average cost of a Fairchild Semiconductor - FDS6679 - Power MOSFET,http://www.mouser.com/Search/Refine.aspx?Keyword=FDS6679
One dollar and one penny USD.
Looking at the second photo down on the Mayohardware blog link, look at AO4407.
(Alpha and Omega Semiconductor)
Look to the right of the Yellow circled AO4407. That small rectangular shaped object, with a dark wide band on it, is a Ceramic Capacitor.
There is one above it of the same size, one above that, and one to the right of the top one.
Average cost of them is around 62 cents to 80 cents.
Average cost of a replacement motherboard is around $40 to $60 on Ebay.
That does it for me right now. Post additional questions in a Comment.
[If you had stated it seemed the laptop came on, but had a blank screen, that is a Different problem ]