I replaced my Dell Inspiron 7548's motherboard after the old one shorted out and refused to turn on. I also had to replace the LCD and LCD cable due to some cracks in the screen and pins falling out of the old cable. I installed the motherboard and when I turned it on, the display remained dark. I tested the screen by holding D while powering on and it worked fine and the backlight turned on too. I hooked up the laptop to an external monitor and the it kept saying 'No Signal'. The laptop fans work fine and change intensity but there are no beeps from the laptop to recognize what's wrong. I reset the CMOS battery, tried the 'hard reset' thing multiple times, and tried all different configurations of my RAM. The only time it beeps is when I remove the RAM completely (2 beeps). I removed the LCD cable and it still wouldn't beep. Please help, I don't know where to start fixing it as I don't even know what's wrong.