PixHawk 4 connect to Pi Zero in 2024

Hi, I’m late to the game but was trying to connect a Pi Zero w to Pixhawk4 FMUV5 using Pi OS and MAtchstic’s guide of 3 years ago: https://www.youtube.com/watch?v=nIuoCYauW3s

but also removed modemmanager

The wiring is correct, all powered by battery, and i keep gettign the dreaded
Connect /dev/serial0 source_system=255
no script plane/mavinit.scr
Log Directory: plane/logs/2024-02-26/flight15
Telemetry log: plane/logs/2024-02-26/flight15/flight.tlog
Waiting for heartbeat from /dev/serial0
MAV> link 1 down

I have tried PX4 and Ardupilot, different baud rates, checked wiring and every fix i could find on the net. Nothing has worked.
Is there a recent guide on how to install, or has anyone done it with latest installs/ software versions that could give some guidance please?

Thanks in advance,

R

@row1 Use Rpanion-Server