I'm having quite some strange and troubling issue. The car was working fine, I parked it, came back 2 hours later and:

• the secondary screen (with the km/h, battery status, etc) is not working
• the main screen is partially working, but it forgot all my radio settings, it doesn't show the battery status, android auto doesn't connect
• the turning lights work, but there is no sound inside the vehicle
• the car is driving fine, but I can't see how fast I'm driving, etc.
• the connection to my cupra app doesn't seem to work
• the car doesn't shut down when I get out of it, or at least the screens don't shut down

Resetting the infotainment system doesn't help.

UPDATE; SOLVED WITH THESE STEPS:

• I disconnected the negative terminal of the 12V battery (in the front hood of the car). It was not easy to do, thankfully i had the right ratchet wrench to be able to access the nut...
• The car was not really shutting down, but it did so when I pressed the brake or accelerator after having disconnected the 12V battery
• I waited for a couple of minutes (not sure if waiting for 15 minutes is really necessary in this case; I repeated the process a second time waiting those 15 minutes because of the next points, but in retrospective, I think the issue was solved the first time around)
• I re-connected the negative terminal of the 12V battery: the car came back to life
• When I tried to start the car (brake + turning the gear selector), a lot of errors started showing up in the cockpit display: ABS not working, power steering not working, etc.
• Those errors seem to be normal, after having disconnected the 12V battery, not just in Cupra Born, but in many other car models, apparently
• I put the gear in "D", and turned the driving wheel all the way to the left, all the way to the right, and then to the center. Then, I turned the car off with the "Start/Stop button". And back on.
• No errors, screens working fine.