You should be fine as far as the tank. "Fumes" aren't going to make their way up to your tank (unless your mod explodes, which, ah, hopefully it shouldn't.)
But, am I understanding this correctly, you put your batteries in, and then rather than locating the screws that fell out, you glued it on? How are you going to get your batteries out for charging, do you plan to use the USB port? If so, congrats, you've just turned your external battery mod into an internal one, if you plan to charge via USB (not recommended with any external battery mod, but probably especially a smok mod, your batteries may charge unevenly, they may be stressed by the USB charge, and once your batteries are dead, you won't be able to replace them. Also, your USB port may fail.
If I am understanding incorrectly and you just used glue instead of screws for the battery compartment and you can still open it well, you should be just fine.
Anna