[q] nexus 5 black screen ( fastboot only) topic

I had my nexus 5 using multirom manager i had liquid smooth and paranoid android roms on it and i flashed ubuntu too the phone was working fine on all of the three roms.. the only issue i had was the microphone that wasn't working on phone calls but it worked only on speakers so i tried to change the mic piece and same the mic wasn't working. So i thought that it was something wrong with the software and i tried to flash a different kernel (Franko Kernel ) and i tried to flash couple GAPPS and nothing still with the mic problem and in the ROM i had a message that says com.play.services not responding so i tried to go on play store and upgrade the services and the play store wasn't working so i dowloaded some play services from chrome, after i installed the apt file i tried to reboot the phone and as soon as i did the reboot the screen had some rainbow an gray colored lines all over the screen horizontal and vertical lines, after that the screen was only black but i could see the backlight on it. I tried to restore stock with fast boot and still nothing i restored android 4.4.4,5.0,5.0.1 and nothing happen the screen was still black, the only thing was that the phone was able to be seen on fast boot and so i thought that the problem was the screen or the flex cable so i tried to buy a new screen i did ordered it from eBay and last night i changed the screen, but nothing worked I'm still having the black screen and the phone is still going on fast boot mode but I'm not able to use my phone... PLEASE HELPPP !!!!