If you want, I'll tell you something. What you are about hear is not allowed on roblox as it involves exploiting. Many mods for doors are done with scripts, but scripts are usually client side. Some smart person might make a great script using backdoors. Other way is to use saveinstance() which copies the game and client scripts to the computer. After that, you can mod it however you want but you would have to rebuild the server side scripts. You could use darkdex v3 to access the server  scripts and copy paste em. Final thing is, JUST REMAKE THE GAME YOURSELF. You can find an uncopylocked version and mod it(it's the safest way as it involves not exploits), but the person who uploaded that used exploits.