The demo wasn't actually working but that wasn't going to matter...until the power went out
Sometime in the last century, I worked for a hot new start-up that was all set to launch its first product at a shindig in a fancy hotel in New York City, along with a full-page ad in the Wall Street Journal, and champagne and jumbo shrimp for all the press and VIPs in attendance.
We had hired top-flight industrial designers, so the enclosure for the hardware looked very cool, but unfortunately, the actual electronics to go inside the box wasn’t ready by show time. The front panel was there, with a little alphanumeric LED status display, so I wired up a battery to the LEDs so that the box appeared to be on, even though it couldn’t actually do anything.
The press and VIPs sat through the executive speeches and PowerPoint slides, and then came and peered at the box, suitably impressed by the whiz-bang technology supposedly inside. Right then, all the power went out in the room. The only thing you could see in the gloom was my battery-powered LED display.
The engineers in the room were horrified – it was obvious now that the box wasn’t even plugged into the AC supply.
We were all set to explain about the imaginary invisible battery backup, but luckily that wasn’t necessary: None of the press or VIPs had noticed.
This seems to be a very known story to me. So many times we had to get ready for a product demo. Believe it or not when "The moment" comes something or the other doesnt work. But yes good that LEDs were working for you. And believe me the VIPs and other big people are not always interested intechnical details.
First, it's unfortunate that you ended up in a situation where you had to dry-lab the demo, but that does happen often enough. What's interesting is the fact that the audience didn't notice.
Perhaps they were all distracted by the power-outage. Perhaps, they really didn't have much knowledge or actual interest in what they were looking at. There's a pretty big lesson on demoing here. If such folks who are paid to write about it, maybe had invested in it, don't even notice a detail like the thing is still on when all the other power is out, then how much of our presentations will they notice?
On the other hand, maybe they were just really impressed that you had managed to design in a battery back-up by launch time.