Broken shift6mq phone - oops I did it again...

TL;DR Be very careful with qbootctl because it can brick your phone. The long story: I’ve a shift6mq shift-phone running postmarketOS and Android in a dual boot (slot A/B) setup. Sometime in December, I had an appointment with my doctor for an annual checkup. I wanted to pay my doctor with my smartphone (Payconiq/Android), so it was time to switch my phone back to Android. Instead of pressing the…