Oh, sorry, didn't catch that part.
Do you mean you want it to look partially broken when you shoot it the first time, and it can be shot a second time, but before getting shot a second time is not solid? If so, then one thing you can do is first have horizontal/vertical triggers placed on the map so that you will be causing their event to be running if you are in a position where you can shoot the tile. Then make your second tile type one that isn't solid, but that NPCs appear beneath. Now place an energy capsule beneath the tile, and have the event check whether the energy capsule still exists or not, and once it doesn't, then have the script destroy the tile the rest of the way. If you're confused, see how this is done in
version 0.96 of my fourth ending mod on map number 10, the Sand Zone. In that version and earlier, that shootable block only looked solid until you tried jumping into it which you could, yet you were still able to shoot it. It wasn't until versions after that that I found a better method by using a hidden heart/missile that was invisible which enabled me to use a solid type that bullets could go through and entities appeared over.
If that's not what you meant and you only want it to be shootable once, and have it not be able to change back after it's become the second type, then simply have the type to the left of your shootable block on the tileset be what type of tile you want it to be after it's been shot. Simple as that.