M17x replaced mobo

I just replaced the mobo of my m17x r1 this morning. I ruined my old mobo as i was changing the graphics card while the battery was in
Anyhows ive previously changed the mobo too and everything was fine, but this time when i turn it on the screen is black, there is a backlight, but no alienware logo etc. Ive tried connecting to an external screen with VGA, the screen doesnt light up at all.
Ive restarted it about a million times, occassionally i get two beeps while the screen is black. If i keep hitting enter eventually it starts beeping every time i press a button. None of the lights on the keyboard or near the on button work.
Im just wondering if it could be a faulty mobo. With my two old mobos that i destroyed myself, the laptop wont even switch on, so im hoping ive done somthing wrong somewhere.

 

Check the LCD connection to the motherboard.

And please remove the power cord, system battery and perform a power drain before you disassemble the system next time.

 

Is bios etc right?....Hope its not bios related and only GPU or display cable related.

 

All connections are in fine, i cant be sure if the bios is good as it is a second hand mobo from the usa which ive waited for like 2 months to be delivered.
ill e-mail my supplier and check it out for sure.
later on ill completely dismantle the laptop and put it back together i might have missed a connection somewhere which may be causing the problem.

 

Hmm. Two beeps mean there was (*)No Memory / RAM detected...as opposed to a memory failure. Do your SCROLL/CAP/NUM light up or flash? If they flash when you boot up, that also indicates some sort of problem.
Also, Check the LCD connection to the motherboard like Katalin said. I've plugged in back in and thought it was secure before, when in reality it wasn't. Had to push that long connector on the right-hand side until it click-snaps into place and THEN I know its good.