So I had setup my Raspberry PI 4 and everything was fine. I received the fan shim and installed it and it seemed to be working. I booted several times. I have not had the opportunity to play with it so it has been sitting on my desk. Today I decided I would experiment with it. I booted up the RPi without issues and did an
apt full-upgrade now I can not get the RPI to boot if the fan shim is attached. It works just fine when it is removed. I am using the official 3A power supply and only attach the hdmi to see what is happening.
I goes into a continuous loop of not being able to read a ext4 partition.If I connect the fan shim after it is booted it seems to work ok.
Any ideas why it wont allow the RPi to boot?
So it turns out it was a corrupt SD card. After only doing a SD card copy to a blank SD and then using that SD everything boots and runs as expected.
Its a bit of a mystery as to why it only was apparent if the shim was attached but that was the case.