I've been working with the T-deck for a while and have gotten into a great many boot loops.

Holding down the scroll ball and restarting as described enters me into an invalid upload mode.

I was finally able to get passed this issue by connecting gpio 46 to ground and then repeating the process involving the trackball.

GPIO 46 was the second from the left on the bottom row of esp pinouts.

The above outlined process fixed my issues resulting from serial data corruption due to bad code and should be mentioned in the documentation for trouble shooting flashing issues.