I got a hint from Mr Castaldi, (aka, "CC"), to use Scaleform to configure the UI. Except, that was even way more convoluted in engine code than the regular stuff was supposed to be. After wrestling with Scaleform and its tutorials from CodeMonkey~ (from Australia?) all day Friday, I slipped in the regular stuff that I did before without altering the GD engine, popped in the Kismet commands to open and close. The UI scene didn't close, but it totally came up. So much for having to mod the engine! At least now I know how, though.
Also, I was working with Zack on getting the inventory mechanic to work (sans the UI). Scott was pulling up good relevant information on the topic as we worked. First, we opened the cell door by touching it. Then, it opened via 'activation' ([E] key). However, the detection was really sensitive. We needed to turn the 'mustAim' property off the trigger. We plopped a barrel in the cell for an inventory key placeholder, picked it up via touch, then 'activate' and created a conditional on the door trigger that requires getting the barrel, first.
I was really overwhelmed this week because I thought my tasks were impossible. I believe we were all thinking, "We are going to totally have to remake this game, now, because we don't know what we're doing." But, I had the attitude, "I'm going to dive right in there, give it my best shot, and see what happens." I guess it worked because now, we're all back on track and should have a game ready for Saturday. It won't be a spectacular game, but it will be a game made within our time limit.