Before you do ANY repair to the OS or file system you have a full backup of what you can't lose. Also W10 versions (well 99% of them) are the OEM license so your license is invalidated with such a change. I have one workaround for the license but about that later.
Your best bet is to try a safe boot and head to the device manager to remove devices in the motherboard area. Here's an article about that. https://www.backup-utility.com/universal-restore/upgrade-motherboard-and-cpu-without-reinstalling-windows-4348.html
As to the OS license you have to deal with this BEFORE the change (how is on the web) but I bet you didn't so here's the only known scenario I see Microsoft issue a new key.
1. The machine is self built and not a Dell or name brand.
2. You call in and tell them your motherboard failed and you need to reactivate.
I have replaced all my computer parts except my hard drives. I have windows 10 on one of them. I thought I could just easily boot up my computer because my hard drive has windows on it. The computer turns on and works perfectly fine but I'm just stuck on the motherboard settings screen, windows operating system does not load. Apparently it's because I have the old motherboard's drivers installed and I do not have my new motherboard's drivers installed. Would I be able to get around this by downloading the new motherboard's drivers onto my hard drive and then trying to boot up?
Any help would be immensely appreciated! Thanks!