I created a button...
This is where you've gone wrong. You haven't created a button, you've created an anchor element. If you had used a button element instead, you wouldn't have this problem:
<button type="button" data-toggle="modal" data-target="#myModal" data-role="disabled">
Connect
</button>
If you are going to continue using an a element instead, at the very least you should give it a role attribute set to "button" and drop the href attribute altogether:
<a role="button" ...>
Once you've done that you can introduce a piece of JavaScript which calls event.preventDefault() - here with event being your click event.