He also received a call from Tesla to check on him. The advisor said that "it is a known issue in the Cybertruck that when you do a screen reset, instead of resetting in the standard two minutes, it takes five hours."
“Car wash mode” just folds in the side mirrors and puts the car in neutral. The need to reboot car is probably coincidental unless there’s some sort of extreme panel gap that let water in and caused a short or something.
Cars haven't needed a car wash mode for a century, but thanks to Tesla innovation you need to remember to toggle a switch before washing your car or it'll break.