Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
There are many models that have the 12 channel moniker on the front.. Could you have a look at this page and see if any of these models match what you have?
If not, could you take a picture of your Garmin and send it to me, so I can visually identify it.. This is important for two reasons. whether I help you fix the issue or help you find a place that can repair it, Ive got to k now the specific model so I can give accurate info!