Had my 2013 Challenger RT in for the alternator recall and now since I got it back the rear window defogger indicator flashes for 20-25 seconds after start up. Has never happened before. Read on line to disconnect the battery and have the controls shut off before hooking battery back up. Tried that but still does the same thing. What causes this and what does it mean. Not in manual that I can find. Can it be fixed or is it to go back to the shop. Like I said has never done this before, only since I got it back from the shop for service.