Yep. The converter wasn't in far enough. There are
three seating actions required.
This site gives a pretty good overview of how to do it, and how to know when it's correctly seated.
Right now, you've probably broken the tabs that mate the TC to the pump rotor. If you're lucky, you can rebuild the pump (although it will have to be pulled; you may want to take it back to your builder to rebuild / remount it).
On the bright side, if you had started the engine, you'd be replacing the pump (not just rebuilding it), and most likely, the converter as well.
Here's another link on what likely happened to you. I don't recall if they mention it at this link, but before mounting the converter, it's good to put in at least a quart of ATF into the converter (more is better, but as long as it doesn't go in completely dry, it's better than starting it up that way.) The first link goes over how to do this.