How can I recover from flashing broken ROMs on my HTC One X?
Download the latest recovery image for your device:

International HTC One X
AT&amp;T HTC One X

Connect your phone to computer via USB cable. Boot your phone into bootloader and issue:
fastboot flash recovery path/to/your/recovery.img
Boot your phone into recovery. Mount SD Card to USB in TWRP Recovery or use adb push to copy your custom ROM .zip file to phone.
Install your custom ROM from .zip file in TWRP.
Extract boot.img from root of your ROM .zip file to your computer.
Connect your phone to computer via USB cable. Boot your phone into bootloader and issue:
fastboot flash boot path/to/your/boot.img
Restart your phone to see if it can boot okay now.