I had my car in garage for a new battery when I got home I noticed my reverse camera wasn't working.

 

I later found out the camera is an aftermarket camera.

 

The cam worked before, please help?

 

Do I need to re programme it or something?

Does it give any message on the screen?

 

I have an AliExpress aftermarket plug-and-play, which occasionally doesn’t work, but it comes on again after a while.  But it does give a ‘parking system not working’ type message.

No message at all the screen comes up with the parking sensors but black behind