YO ! I was so disappointed when i got an EOS 40 D body to play with from a Camera Club member as it will not work -- all I get every time is message 'CF card not Formatted, Format Card with this camera' so I find FORMAT in MENU and click OK and another message says ' Cannot Format, change the CF Card' -- so even with a DIFFERENT CF Card I get the Same Messages even though the different card HAD been Formatted. . In the top LCD screen it says 'ERR CF' -- and there are NO bent pins !
The error is a connection/communication error meaning it does not read the card. How sure are you that there is not a bent or damaged pin? 2 cards validated as good means it is the camera that is a problem. Its kinda hard to inspect the pins without digging into the camera, given the pins are deep inside the camera. You could have a missing pin which already broke off.
I contact CANON U K and technician said as it is 17 years old they no longer Repair the EOS 40D I also had a look at installing FIRMWARE but it would not let me -- a case for THE BIN perhaps ?
Yea i mean the firmware update would be using a CF card i believe since the 40d uses EOS Utility v1 which you cant even download anymore. But to your question/point, the 40d is worth maybe $30 in good working order, i know they go for more on ebay, but you have many newer cameras you can find win good working order locally or on ebay for $50-100 if you looking for just a modest priced / beater camera. Definitely not worth repair costs, unless you can do it yourself.
Even if the pins aren’t bent, dirt or oxidation can affect connections. Use a clean, soft brush to gently clean the card slot. If possible, update the camera’s firmware. This sometimes resolves card compatibility issues. I would recommend, format the card as FAT32 on a computer, then insert it back into the camera and try formatting it again there.
I had the same issue with my EOS 10D, no apparent damage to the pins, I think the cp card I was using may have shorted out one of the components in the camera as the same thing happened to another of my cameras.