I'm really not a mechanics specialist (I've only trained as an electrician so I have the basics about electric things), so I hope my question won't sound too "weird".
So, I tried to install a wired rearview camera on a Peugeot 206 car. I first connected two wires in the fuses box (one in a fuse slot powered when car is off, the other one powered when it is started), but then I couldn't find a place to connect the ground wire, so in the mean time I just used the cigar-lighter socket to power the screen. I also connected the rearview camera to the the reversing light. When I started the car, all went well and the camera worked fine.
I stopped the car, and tried to start it again a few minutes later. At this moment, the car didn't start, I heard clicks, and I saw a message about an ESP default. I tried to disconnect everything I did but it didn't change anything. The car still doesn't start and I still have an ESP warning. I checked the fuse I took off and put back, and they're ok.
So I'm really confused about what happened. Did I make any obvious mistake or something? Which way should I look to find the source of the problem?
Thank you in advance! PS: I'm not sure about the tags to use for this post, please don't hesitate to correct me. I hope my question is not too "awkward" or something.