EFI fuse got melted?

Yes. You have a short that caused the issue but if the fuse is melted then most likely it was the fuse itself or module. If the computer is slightly burned that is just another sign that it got hot. The fuse is supposed to pop and not melt so I am thinking the fuse may have been incorrect and too large which caused it to melt rather than blow.

Here are a couple guides that will help with this:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

I am also attaching the info below from the manual on how to test this. Please run through this info and let us know if you have other questions. Thanks