I have one of these - it's awesome, I love it and I think it's an incredible success for a first hardware product. My takeaway from reading this is that caring about building a great product made a huge difference in how your first 500 units landed. Now the next batch gets to come with all those learnings.
I'm sure there will be more challenges as well but as long as you keep focusing on the experience you're delivering, I'm sure you'll continue to get past them