Does anybody have instructions or guide on how to properly replace the airbag module cover ONLY and not the whole Airbag Module Assembly?
That is a no no. I have opened up airbags in the past and let me tell you, you don't want to mess with that. Behind that is the airbag. And even though it can come off, there is a good chance you will not be alble to reinstall the airbag properly. Plus the risk of the airbag deploying while you mess with it.
In additioin, if you glue at the crack, you may cause unforseen problem if the airbag has to deploy. Where you have the crack is where the airbag will open up in case of an accident. You don't want to make that stronger bond than what Hyundai designed it for.
I love fixing problems myself but I would not do fix.
Buy a used airbag online and be done in 15 minutes. They are quite cheap for that car.