One thing you could do now that you think it is a jam or some issue, it is probably sending out an error if it is turning on.
Plug the card reader serial into an esp32 or pi whatever you have and read the incoming. It might give you more info, and you can even emulate what the naomi2 sends back out. So you can see how it responds.
Plug the card reader serial into an esp32 or pi whatever you have and read the incoming. It might give you more info, and you can even emulate what the naomi2 sends back out. So you can see how it responds.