Why do all car doors and the trunk lock unexpectedly on our 2015 Hyundai Sonata.

2015 is it under warranty? Dealer repair no fee.

Yes. Thanks.

My dealer doesn’t know what to do. Can someone advise what the dealer should do to prevent from happening again?

The car is supposed to automatically lock on doors once the car's running and in motion. I've mice who visit my car and occasionally trigger unlock on doors and trunk when not running/not moving by chewing on my wires. Check their preferred locations: air filter and cabin air filter. If you find signs of them (chewed filter, leaves, etc.) get Granpa's Peppermint from Tractor Supply, spray the new filters with it, and replace. They hate peppermint. If lock/unlock is occurring when not in motion, and no sign of mice, you either have an electrical short, or your car's software may need reinstallation. Good luck.