Well, safes are meant to be difficult to open, so unscrewing the 4 bolts on the top won't let you in. And since we are here, neither unbolting the hinge would.
If you want to use it as a safe after you've opened it, a professional opening is what you need. Or you could contact a
teacher in Illinois and ask her students for help.
If you want to open it hoping there's something valuable still inside, let me make an educated guess: it's empty.
Whatever you decide to do, stay safe
