Headache with Car Radio.

[YodaBird]

I rarely use my car radio, including the DVD player, back in August of this year; after the radio not being used, not being used as in not being turned on for months, upon months, all the AM channels don't work.

I brought the car into the dealer, they simply just reset the battery, in hopes it would solve the problem; unfortunately it didn't, the AM radio continues not to work.

Recently I re-visited my dealer, this time, they unscrewed the antenna while the car was on, when the antenna was screwed back in the radio screen in the 2012 Yaris was red; rather then the default light yellow / white color.

What is going wrong, did someone, somewhere unscrew the antenna or shorten the radio; numerous guys at the dealer said it's, weird.