Moto G stuck on the screen "Warning bootloader unlocked"
Bootloader is a bit of code that tells your device's OS how to boot up? Does the phone boot in fastboot mode? If so you can tape fastboot oem lock or an alternatie that works on many motorola: fastboot oem lock begin this should relock the bootloader.

To boot in fastboot mode: Turn off your phone and then press and hold the Volume Down + Power buttons simultaneously for a few seconds.

If the above dont work, you'll need simply to flash the stock firmware first and then get in fastbootmode and tapefastboot oem lock

This thread on XDA Developers will explain more in details.