I have ran into this exact issue before. This error only happens if garmin cannot read the card. If it can read it and the config is jacked it will still boot. You would have some weird config problems in that situation. It won't display the config module missing message. As George mentioned, the config module is most likely not plugged in correctly or the main connector that has a very small cable is not seated properly. Bouncing around could tweak the small cable and pop it out of its seat. Try everything you can first. Rebooting, software update if it will let you apply one, etc. If nothing else works dive in. It is easy to take the housing apart. The hard part is getting to it. Just be careful with the screws. They are tiny. Easy to drop one behind the panel.