Mercedes wont start any Mechanic input

Tempe AZ

Description

C300 2008 Mercedes new battery in Nov I have to start slowly click 123 allow the radio to come up from console then turn it on otherwise the battery is dead,... but then this week AAA jumped it, let it run 30 mins shut it off the radio only goes half way down, and its dead again its not starter or alternator or battery I think it may be electrical, is this common APPRECIATE any input..trying to find a certified MB TECH Thanks Kris