We wanted to make sure it wouldn't leak before we put our computer and electronics into it. So we dropped it into the water empty.
The latches fell off and it sunk.
The meeting wasn't a complete waste because we have a plan for attaching the end caps in a much simpler way.

We also have some new electronics. At this point the motors work remotely with a joystick, but we got some motor controllers with a high amperage rating, and they're pretty unstable. We're trying to get our money back from the company.
Here are the motor controllers we're trying to use.
We got the 5 amp version running just fine, but the 10A ones fall asleep after a few minutes and then refused to respond to any new commands.