Since you have to change firmware anyway - try the version of grbl that I posted for the laser group. It has a lot of testing on it and that’s the version I’m testing with.
Here’s the link if you want to test with it:
https://discuss.inventables.com/t/xcarve-jtech-grbl-update-bug-fix/28943
Post or send me a PM when you start testing and I’ll try to work with you to get it going.