Battery Drain/Service Trailer Brake System

[LaToja49]

Hi. I have a 2015 Tahoe LT. I took it to the dealership for an oil change and fix a recall (computer update to make the brake pedal more stiff is what I was told). Since then, I've noticed when I hit a bump the radio cuts off, the AC flickers, and the dash screen flashes. The dealership said they can look at it but if it wasn't related to what they did = $200 diagnostic fee. My usual mechanic said he's seen the issue quite a bit and usually recommends an after-market radio as the factory radio is what drains the battery. Has anyone dealt with this before? How did you resolve?