New 7C80 Install Help

After comparing all the options I decided a 7C80 and LinuxCNC would be ideal for my Bridgeport CNC project.

I tried using Balena Etcher to install onto a SD card, but when I try to boot the RPI it doesn't appear to be a valid flash. What could I be doing wrong?

The 7c80 arrived today, are there any tutorials or build threads around that help avoid common pitfalls or show best practice for setting this up?

How are MPG inputs configured?

Will be using NEMA34's on all 3 axis with closed loop drivers, VFD and a 1024 spindle encoder. Many thanks.

Downloading the manual from the Mesa web site should be the first step, it has all the information needed for setup and much more, but do skip the "much more" part as that is not needed, usually.
A rough guide would be to plug the RPI, connect the power ( make sure the polarity is correct), boot Linux and LinuxCNC, use mesaflash to read the card configuration to make sure everything is working and communicating properly, make a rough config just to get things going, start wiring stepper drives-check if they work, wire inputs and outputs - check if they work, wire MPG - check if they work, etc etc
Never wire everything and power the card, that usually does not end well.

Is this board not commonly used for LinuxCNC? It appears to have excellent specifications.

Is the Pi iso on the site suitable for Pi 4? All i am getting is the rainbow boot screen. Tried multiple monitors, and multiple SD cards.

linuxcnc.org/downloads/
The RPI4 image is there.
BTW, nice nic, watched "Hackers" lately?

hmm, fresh download and SD card, still rainbow screen.

How's your power supply & power supply cable. They can cause that issue, my son had that issue and a quality cable & power supply fixed it.

Power supply and cable is good. Popped in a different SD card with PiHole on it and it booted right up. Flashed LinuxCNC 2.8 Pi4 onto same card, same rainbow screen and stopped there. Tried a TV, a monitor and a 7" LCD (with correct config.txt). At a loss if this is a bad IMG file on the site or something else.

zaphod.unpythonic.net/pi/image_2020-09-05-linuxcnc-pi4.zip
I used this image last week and it went flawlessly. SSH into the pi and see if that works with that img, and check your config file to make sure you are loading the correct kernel. If its loading a different kernel, change it back to default kernel7l and see if it boots, you can then at least use the monitor to correct your kernel issue after. The 2 main reasons I would get rainbow trying to do linuxcnc images were either a kernel issue or default graphics setting. If you are plugged into the 7c80, unplug it first, and configure pi before working with the 7c80