Volume up button. Volume down button. Press and hold the side button. When the Apple logo appears, release the side button. Had to reboot my phone using Apple's instructions to get the touchscreen working on Saturday
I followed these instructions from Apple : Force restart iPhone after Saturday’s touchscreen woes in the Vancouver temperate rainforest rain: January 31, 2026: Touchscreen buttons on iOS apps eg, Apeman rear video mirror app, don’t work on my iPhone16 Pro Max in constant rain