Post a pic inside of the coin door, along with a pictures of the credit wheel from inside the head.

There are several ways to get an EM to free play, and without seeing what was done, it would just be guessing.

Also, how many games are showing now in the credit window?

Yes. The back is removable. There should be a keyhole to unlock it. If you don’t have the key, look closely on the coin door or near the coin door. Often there’s a hook that holds the key you need.