Audi Concert 2 Red screen and no response from buttons

Hello I unplugged my Audi Concert 2 from my car an left it out of the car unplugged for some time (more than a month). Than when I plugged it again and I had red screen (seems like the back light of the screen ) I took it off again. I opened it and dried with an hair drier. Then I plugged it back again, it started to work for some minutes and then nothing . Does someone know how to fix these tipe of problem?