Hardware hacking, finding UART

A few days ago, while casually scrolling through a news
aggregator, I stumbled into a video entitled "Hacker's Guide to
UART Root Shells"[1].

In short, the explained technique boils down to finding a
possible UART on the PCB of your device, using a multimeter to
verify if the candidate has indeed the characteristics of a UART.

I managed with little effort to find and connect to the serial
console of a few devices: an old set-top-box that I found when we
moved in, and my old ASUS router.  None of them allowed me direct
root access via serial console, but as mentioned in the video, it
is very good to be able to get a visual feedback on what happens
behind the scene during future penetration attempts.

[1]: https://m.youtube.com/watch?v=01mw0oTHwxg