Actually, the blinking headlights sounds like a factory alarm that has been triggered. Key switch shuts the car off because the vacuum circuit works - nothing electrical there. But all the other electrical stuff not working could be because of the alarm. In other models, the alarm module is in front of the passenger's footwell - you lift the carpet and it is along the firewall. Then just unplug the module. Hopefully, you will find it there.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References