[anon9001]

> With uart output.

Not super familiar with hardware hacking. Does this essentially mean you plug in the write wires, run minicom, and get a terminal with a shell?

[Jenda_]

You may get a tty with no getty/shell running, you may get a getty login prompt (which was probably this case, as the author proceeds to login as root with an empty password), you may get a custom CLI that only allows you to set some device parameters but no arbitrary command execution.

[contingencies]

You get a potentially bidirectional serial interface. Whether there is a shell running or any input accepted is another question. Very often they are output only, merely for debugging.