I recently bought a Roborock S6 MaxV and am trying to figure out where (if) I can find UART on the board.

The board on the S6 MaxV is substantially different from the board on the S6, shown in #213. I found what could be same cluster of pins (except TPA8 is TPA4). Those pins are nearby the SoC, so that might make sense - but it has a rubber pad over it, so I can't tell which it is. It's not Wi-Fi, as that's on a daughterboard.

TPA4 (what would have been 8 / TX on the S6) and TPA15 both show 3.3v during boot.

TPA16 (maybe the same on the S6?) shows some mystery 500khz signal, which is the wrong frequency for 115200 baud (or really any common baud rate - I can't set my UART to that). I'd normally accept that it's just not the TX pin, but this is the only test point anywhere on the board that's not giving me straight DC.

The actual TPA8 on this board is ground - it's in the upper left of the photo.

Any pointers on either what I'm looking at with the mystery signal, or where I can find the UART pins, would be greatly appreciated.