I got a lemon. Help lol

[MileyFinley1]

A follow on from my keys post.... my newest issues include,

reg lights not working at all, changed them for 2 different bulbs and still off.

Audi concert radio keeps randomly dropping signal to static. 

Windows keep randomly rolling themselves all the way down. Doesn't matter if the car us open, ignition is on, they did it while I took my kids to the park while car was locked. And they did it earlier while I gad ignition on and I was changing sidelights. 

I've accepted I got a lemon but I'm now determined to put the work in to get it right.

[Steve Q]

How old is the battery? 

That'd be my first port of call as a failing battery can cause various electrical gremlins or a diagnostic check to see if any fault codes flag up