It is a strange thing that in my garage days when cars had a choke cable, one immediate pointer to the sort of problems caused by a poor earth, or battery connection was the choke cable used to get hot.
Now with manufacturers cutting pennies off the parts that make up a modern car it is no wonder that unless you keep on top of maintenance problems arise. Not major but minor problems that can cause may hem.
Yes the black bit on the screen is the sensor for the lights and wipers.
Lastly, go back to the dealer and if necessary put the sale of goods act where he might not like it but as you area Lady you won't be as coarse as us blokes
I have had problems with BT but when I threatened Ofcom, even I was surprised at the different attitude. You paid good money make them stand by the vehicle they sold you, good luck