Honestly I don't know what could be causing all those problems. Thought maybe the onboard 5V was wigging out, causing the USB chip to cycle on and off which would explain the disconnects, and also cycle the microcontroller and temp sensor so it keeps starting up to invalid state and blinking. But the timings don't make sense.

It's unlikely to have a bad temp sensor causing the blink. It's at least as unlikely to have a zero-chips-detected issue. It's basically impossible to have both. Did someone play baseball with it or something?