In general, try plugging a different device into the same wall outlet like a smartphone and a charger to test the wall outlet is supplying power. Otherwise, give it an hour to cool down, because the thermal fuse has triggered. During that time clean and inspect all the hoses and airflow pathways.
Overall, start by resetting your WiFi modem, then restart your robot vacuum. After that, restart your smartphone, and uninstall and reinstall the robot vacuum app. Finally, if it’s still not connecting to WiFi check the owners manual to see what WiFi band it needs to be, steps explained below.