As someone who used to work at an IoT company the consumer space is brutal. Unless you've got something you can sell for 10x BOM, or there's naturally a subscription based model then it's not worth the blood, sweat, and tears.
10x BOM? Why is the bar so high for profitably? There are manufacturing costs, marketing and inventory risk. But still… what am I missing?
Maybe 2-3 share a single root cause, and it's not clear how you'd prevent this from happening in the future.
If you're shipping large volumes, this can add 10% to the MSRP, but if you're shipping low volumes, $50-100/hr of weeklong diagnosis and investigation can easily add 50-300% to the price of each unit.
And that's if everything else is going perfectly. Which means you lucked out and found an amazing Chinese contract manufacturer who works with you hand-in-hand to fix any design bugs and manufacturing issues, and ensure parts availability.