PLEASE HELP Moto G4 fastboot broken
Your "Invalid Bootloader State" is because your device is already unlocked. You cannot unlock it again.

Moto devices do not support downgrading officially. Preflash Validation is an error that means the images you attempting to flash is older than what is already installed. You need to flash an image that is at least version NPJS25.93-14-4 or newer. A good source for Moto firmware images is firmware.center at https://firmware.center/firmware/Motorola/

Inside the image is a file called flashfile.xml which will contain the steps necessary to properly flash the image with fastboot.