We tried to Jump the car, but of course broke the golden rule, DON'T CROSS THE WIRES!! Now there is nothing happening after I have switched in a Brand New Battery. Are there some simple test I can do to check, or is it too late for anything?

I guess the first thing I'd do is check all fuses and replace any that are burnt. If that doesn't work, see if any wires are burnt.

I'm not a auto mechanic, but I did make a similar mistake on one of my cars years ago. When I did it, it fried the voltage regulator. I assume that battery voltage can fluctuate at different times, and for that reason I think that is why the regulator is there. Maybe a question for an auto parts person. They may be able to shed light on if your car has one and where it is if it does.

Check the main fuse in the under hood fuse box. (and all others) I am sure you will find it burnt.

We tried to Jump the car, but of course broke the golden rule, DON'T CROSS THE WIRES!!! Now there is nothing happening after i have switched in a Brand New Battery. Are there some simple test i can do to check, or is it too late for anything?
MAin fuse - underhood.

It's held in with screws.

The same thing happened to me. U just needa change the 80A fuse in the fusebox under thte hood. You probably wasted your money getting a new battery though :(

Check the main fues if you have not already, mine is an 80a... first stop after the positive post and should be marked on the cap of the fuse cover.
Because