I'd say the answer to the fix would start with a swat up side the brother's head. lol

As 6464s says, you need to make sure both the hood latches release. You may have to remove the grille to actuate the hood release.
Once the front end is released, do not just lift up on the front end or you may buckle the hood or at lest distort it.
Try to work your fingers or a suitable tool up along the sides of the hood until you get tho the region of the hinges. Pull up gently - it may help if one person flexes the front of the hood slightly to work a corner loose.

When you do get it open and properly aligned, mark the location of the hinge levers on the hood brackets they bolt to, so you won't make the mistake again.

If it is an original mini, first, you have to get the pin to release from the catch at the slam panel. Once that is done, you will need to loosen the four nuts holding the back of the bonnet  to be able to move it around. The trick is to make the nuts snug enough to hold the position you're happy with yet be able to move the bonnet if you are not. It takes many trial and error actions to get the spacing right around the cowl and the catch to work perfectly, all without damaging the paintwork.

My brother installed the hood wrong and it now binds on the cowl and will not open. How can i fix this?