2007 Xk. My infotainment system was working. I had aaa replace a old battery My infotainmenst system was working that same day after batter instal. and turned off and 6 times. The next day my infotainment system went black. The mechanic at Pep boys could not figure it. The fuse is fine. the infotainment system is not blown. I was told maybe need to be reset after batery install? How do i do that? or what else can it be?

 

CHARGE your new battery! Your 'new' one evidently is in worse shape than your old one was. New batteries very rarely come fully charged.
A ten-amp charger overnight or longer (24 hours?) would probably be very beneficial.
Start there, and see what happens.