2006 Chevy express 2500 van

I have a 2006 Chevy express 2500 van and when I shut it off take the key out
and open the door sometimes the interior light won’t come on and the radio
doesn’t turn off? When I play around with the door latch on the drivers door or
the passenger door it will then turn on the light and turn off the radio. Also I
have a alarm system and during the night sometimes the alarm will check itself
like someone was trying to open the door.