Me and him have Java installed and I helped configure his machine and Minecraft and all that other shiz, also the script is:
java.exe -server -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -Xmx4096M -Xms4096M -jar forge-1.12.2-184.108.40.20646-universal.jar
This is the exact script that I use for the server and it works and everything is fine, but when he tries to run the script it just doesn't work and I told him to paste the script in the start.bat and it's the exact same. He hasn't altered anything but still doesn't work.
But he ran the Java instance of the server and it works but none of the mods load except for about like 2 or 3 mods, but when I run the java instance it's all fine and works.