the lcd screen had gotten broke and so i had ordered a new one before i had removed the LCD screen it would power up fan and everything would power but i replaced the screen and it wont power up at all i would get the number lock caps lock and scroll lock then the power light would come on then shut off please help if you can guys *P.S i have placed the old lcd screen back in but still no luck
I doubt that the problem is the new LCD. Check to make sure that the antenna cable is properly connected. It's possible that you damaged the connectors when you separated it or attempted to reconnect it (you have to be real careful not to apply force if its not properly aligned, as the parts are quite fragile), in which case it may need to be repaired/replaced. At this point you may be best served by taking it to a professional to properly diagnose and repair.
I don't know what an antenna cable has to do with the notebook turning on...that's nonsense.
If you've already re-reassembled it, it's time to breadboard it. Take the machine apart, remove the motherboard (and every other component), and put back on the CPU, heatsink, and one stick of RAM with the motherboard outside of the casing. Plug it into an external monitor and keyboard, and try to power her up. Then, keep on adding one component at a time until you get a configuration that doesn't work; then, you've found your problem (assuming it starts the first time - if it doesn't, you probably have a motherboard issue).
Er, not the antenna cable, I meant the cable on Dells between the hinge cover and the base of the unit. If that isn't properly connected, then the obviously the power button isn't going to work.
If the problem didn't arise until he disassembled to install the new LCD, chances are it's not a motherboard issue but a loose connection somewhere. If the OP doesn't want to pay a professional to look at it, consider purchasing a new hinge cover and trying that. You can find them (used) for a few bucks on eBay.
I still don't know what you're getting at. The board that contains the power button has a cable that runs directly down to the motherboard in every notebook I've ever taken apart. Why would it run through the hinge? There's no point in putting it there. Generally, there are 4 cables that run by the hinges - the display connection, two antennas, and a webcam connection, if available.
A hinge cover is just a piece of plastic...why would getting a new one make any difference? If the OP has already disassembled and reassembled the notebook 3 times, I'm pretty sure he's (or she!) good enough to do this without having to pay someone else to do it.
On my old Dell 9400, there is a cable that connects the hinge cover to the base of the unit. I was thinking that all Dell laptops had them. Although I just checked my wife's 6400 and the D630 that I'm writing this post on and neither have it, so apparently it's not very common. That not withstanding, it still seems that the most likely culprit is a loose connection somewhere, not a motherboard issue.
As for your last point... anyone with an IQ above room temperature can disassemble a computer--the expertise comes from being able to properly put it back together afterward. That the laptop will not power up indicates that something went awry, which indicates that a professional might be able to spot something that the OP is not able to see.
Sure, maybe the pro can solve the problem faster, but with some help from us, the OP can solve the problem his/her self, too. It's just basic troubleshooting technique. If you've got a brain good enough to disassemble it, you've got enough logic in your head to be able to troubleshoot it. You don't even have to know anything about how it works, either. It's how everyone starts.