If you replaced the mainboard, screen, and used different sd cards. Then the only thing would be the CM4 or assembled wrong. The fact you’ve put it together multiple times now and it looks good in the photo makes me think the CM4.
I assume this is the image you’re using. http://dl.clockworkpi.com/uConsole_CM4_v1.3g_64bit.img.7z
Here is my custom image in case they changed something in the newer CM4s that would cause the older 5.10 kernel to not work. It probably wont work either but it wont hurt to try.