A lesson every engineer needs to learn: first, write the user's guide.
No real engineer likes this idea but they either listen to the crusty old geezer who's been around forever, or they learn it the hard way. You can put a lot of time and energy into a really awesome design only to realize, after the prototype is built, that you need one more button. Yeah, learning things the hard way tends to be embarrassing, not to mention expensive.
So, since I'm now the old geezer that's been around forever, I took my own advice and wrote the user's guide.
You can download the pdf here: SmartLid User's Guide
To be honest, we were a little surprised to realize that we'll need eight buttons (we haven't updated our graphics yet.) True, we could overload some functions onto other buttons but that tends to also overload the user.
The biggest unknown is the back light; we're concerned it will drain the battery too fast and we're not sure it's really needed.
Please add your comments down below; it's easier for us to keep track of them and others can share your insights.
Also, be sure to check out Tim Layton's excellent tutorials here: Tim Layton Fine Art