Curious how he actually pulled that off because 15 words in 20 minutes is way better than most dry electrode setups I've seen. Was it a P300 speller where you stare at flashing letters, or was he doing motor imagery where you imagine moving your hand? Those two work totally different and the P300 one usually needs you to sit still and not blink, which drives me nuts. Also did the headset need saline or was it dry contact? The dry ones I tried had terrible signal once you moved at all.

Wait, "the trust was gone"? Over a button? That is wild to me. I get that they built their whole weekly thing around it, but you offered to rebuild it in a week and they still walked. That tells me it was never really about the button. It was about them feeling like you didn't care enough to even ask. Losing 74 grand a year over something two accounts used back in 2019 has to sting, and honestly I bet your gut is right that there are other cuts like that you never heard about. I have seen people try to win clients back by rebuilding stuff and it almost never works, because by the time you are rebuilding it they have already moved on and found something that fits.