replaced laptop pcb, but screen does not turn on. Same pcb part number but slightly different hardware configuration on new board

Hi, a friend brought his laptop to me because it would not power up or do anything. I took a look at it and after a few tests I concluded that the motherboard was bad. I located the part number on the motherboard and found a replacement that had the same part number and same revision so I ordered it.

I took the original board out and found lots of dust in the fan vent, so that is probably what caused the original problem (from overheating since the vents was more then 85% restricted) and I installed the new board and I noticed a few small differences in the two boards. The first differences I noted was on the replacement board there is no hardware connector installed  to connect the right side speaker. I see the designated area on the pcb, but there is just no connector soldered on. The other thing I noted was there was also no hardware connector to plug the right side usb card into. But those are minor issues, if one speaker did not work and one side of the usb ports did not work It is not that big of a problem. So I left the usb card and the right speaker unplugged. I hooked up other components and  did a power up test before I put all the screws back in, and I  the laptop power key now illuminated when I pressed it (it did not with the original circuit board) and I could also hear the fan spinning and hard drive spinning (none of them worked on the original board).

The only problem is the lcd does not illuminate.

I also see on the replacement board there is a connector soldered to the motherboard that is for the touch screen. The original board does not have touch function, so the manufacturer did not install the hardware connector on the original board.

So is there any other tricks to get the screen to work? (maybe re flash bios or something?) Or would I have to buy another board that does not have the touch screen plug hardware installed?

In the attached photo I circled the slight differences in hardware.

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☠ MASQ ☠Commented:
Are you sure about the replacement board part number?

This looks like a DV7 you're trying to put a DV6 board into ...

Flip the boards over - on the SODIMM RAM slots you should find a pair of white stickers (or on the black plastic insulator strip a single sticker) labelled "Replace with HP Spares - 6xxxxx-00x" - That number including the three digit revision number at the end identifies the exact board specification - the number printed on the main PCB ( DA0LX6MB6H1) is common to most of the DV6 & 7 mainboards - it's the components attached to the board that make the difference.
where did the replacement board come from?  ebay?  probably the wrong board, as Masq said

you can look on the hp sites for the correct board for that model
what model is it ??
hydrive1902Author Commented:
Hello experts, sorry I have been away for a few days but I am back once again.

Both model numbers appear to be the same. You can see in the blue area in the photo below (the installed board is the new one and the one below it is the original). Both boards do have the same model number which is: DA0LX6MB6H1 REV. H. But as you can see in the red areas that I flagged, some boards appear to have different components on the circuit board.

Also yes the replacement board was from ebay

☠ MASQ ☠Commented:
Please read my comment again - the number you are highlighting in blue is generic to a large number of PCBs used in the HP DV Series which have different specifications - the actual number you need is on the other side of the board and not in the photograph.

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hydrive1902Author Commented:
thank you, I will look at the sticker first next time
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