So I turn the car on it says Nissan. Navigation with black screen then goes black and then blue screen appears saying no SD card i took it to dealership they say it won't let them reprogram the SD card and that the obd2 is says it has a system malfunction it's 4200 dollars to replace the head unit the car is not worth that the part is 3000 please help me fix this I can't afford that I just brought the car. Dealership aslo said they unplugged and replugged in the unit. However I have this sinking feeling they didn't even touch the car as the head unit looks like it's never been touched like the seals are still in place