Faulty printer firmware?

I bought a Dell 2330DN and when I first used it, it repeatedly gave a jam error despite being no jam. This was the first sign that something was wrong with this printer.

I downloaded the service manual and checked all the connections to the controller board are correct and blew compressed air into the sensors. No effect. I then entered service mode to test the sensors. The odd thing was that the sensors were triggering the wrong values in the printer, the second bad sign.

I then did a...

Faulty printer firmware?