Darkweasel30

I installed an aftermarket multimedia player on my 2011 C300 Sport, everything works fine. I turn off the ignition, open the door the radio turns off. I turn on the car and it still works fine. problem is after at least 6 hours of the car being off the new radio is reset to factory settings which means it lost power while it's off. Any idea what's wrong? Thanks in advance for help.