Depending on how grub was installed, you might need to boot a live environment just to tell your new mobo about it. You can skip chrooting if your live media has efibootmgr and you can figure out how to use it, but if that fails you can always chroot and install grub fresh.
Also, it might just work.
I still recall to this day, one of my university tutors talking about the C fastmath compiler directive: “I do not need a computer to arrive very, very quickly at the wrong answer; I can do that myself.”
It’s good to see that with applications of modern comp-sci we have graduated to arriving very, very slowly and at great expense at the wrong answer.
Just make sure you put it on the right disk, if you go that route ;)