Unfortunately the rom is not complete. We need a boot img, if you could get a dump of boot img, unpack it edit & repack it we could be in right direction, another thing is obtain system dump gunzip it & flash via fastboot(i've tried & realised it requires a system.gz format to flash succesfully) work out on boot img & let me know of progress.
Unfortunately in the listed roms at xda x500 is missing, tried flashing phone with intel flash tool evrythng flashes succesfully. Only missing files are boot img and sytem files. Fortunately bootloader not locked.