Hyundai Repair: battery backwards, fuse boxes, fuse box

Question
I accidentally attached the battery to the wrong polarity. Now it will not start. While connected it made the horn sound. After reconnecting correctly it just turns without starting. Many of the fuses look fine. I don't know how to check many of the fuses under the hood since many of them don't aren't translucent to see indications.

Answer
Usually this blows one of the main fuses along with one or two others.  All of the fuses should be able to be inspected-- either they'll be translucent (various colors) or they'll have a clear plastic top which you can look through.  Items in the underhood fuse box which appear to simply be small plastic boxes are relays.

Start by inspecting the main fuse.  Depending on the year and model of your car, it'll either be at the positive battery terminal or in the fuse box.  Again depending on the year and model of your car, the main fuse will either be a large fuse with a clear plastic cover or a bolt-in flat fuse.

After resolving any issues with the main fuse, then inspect all fuses in the underhood and dash fuse boxes.  Again, if they're actually fuses, you'll actually be able to visually look to see whether the link inside is melted.