[Nexus 5X Q&A, Help & Troubleshooting] Nebula666:
Long story. I downloaded the Nexus rootkit and unlocked my bootloader in an attempt to root my device. I installed TWRP and erased all my device information without making a backup. During intallation something happened with the toolkit(I believe the program froze or I just got too impatient, so I disconnected the USB). Mind you at this point I had not installed any third party roms yet resides TWRP which I don't even know if it installed completely because after I disconnected the screen turned into bright static.

So after mindlessly disconnecting my phone the entire screen went blank or was static. I could not see anything, so I sent it to LG for repair. They fixed the screen, but the phone is still without an operating system because I wiped it when I had TWRP and I now see this after it loads https://goo.gl/photos/pNZz2XgpQ2oA3SMN6 I don't know what else they did over there because I no longer have TWRP. I also have a locked bootloader now. I attached some screen shots of what options I get when I turn on the phone and the other options I see. which include the bootloader and recovery screen.

https://goo.gl/photos/w7QnfuqtbNGirQuE9

https://goo.gl/photos/58XmdAiMwmdvGfr29

I have tried using the rootkit to install stock rom, but that requires an unlocked bootloader which I don't have. I also tried fastboot oem unlock, but it says failed. Also, I have tried installing the right drivers... It's hard to tell whether or not I have the correct drivers. Under device manager. I am seeing; Android Device--- LG Android Interface. I don't think these drivers work though because I can't pull up my device details in ADB (I am now able to do this thanks to some help in the forum)

EDIT: I fixed the driver issues, This involved manually assigning drivers TWICE through device manager. I had to assign them when I was in the bootloader and again when I went into recovery on my android device. Windows 8.1 recognized the device as 2 different devices based on what screen (bootloader vs recovery). Thus make sure to manually update your drivers twice. Once in bootloader and again in recovery. I am also using the latest android SDK platform tools.

I am now having trouble doing "adb sideload file.zip"... My device keeps rejecting googles OTA files saying signature verification failed https://goo.gl/photos/9UURn9To33YdZM7B7

I also get this error in CMD https://goo.gl/photos/dRvUS3bB5saGehX1A

EDIT: added more details

Last edit: Solved!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

So none of the OTA roms from google worked in ADB sideload etc, but for whatever reason when I sideloaded a custom ROM it installed just fine... No sig verifications errors in recovery mode... I used http://xdaforums.com/nexus-5x/development/rom-pure-nexus-layers-fi-wifi-calling-t3244601 <---- After downloading this custom rom file, I moved it over to my SDK platform tools folder (you could also use the adb folder in your C drive if you went about installing those adb drivers)

Next, I started bootloader on my android device by pressing power and volume down buttons. I then navigated to recovery by using the volume keys. once in recovery, I selected apply update from ADB. I am now done with the phone.

I opened up command prompt from my PC using shift/right click from the appropriate folder (c/adb or platform tools folder). further, I opened command prompt and typed in "adb sideload pure_nexus_bullhead-6.0-20151109.zip" the flash was successful.

The first boot was not perfect. I recieved a error in regards to something about a manufacture error, but it was enough for me to get into the OS and enable OEM unlocking. I am now able to move forward and unlock the bootloader with rootkit or fastboot. After unlocking the boot loader I went back to a factory ROM which now installed with no problem.

Holly crap. Anyways huge thanks to everyone on this thread you guys are awesome I could not have done it without you.

XDA 4 life