How to fix Apple iPhone 6s that won’t turn on

Continue troubleshooting your iPhone by looking at a few key aspects that will help you figure out what's causing the issue. If your iPhone still won't switch on after a force reset, here are a few additional things you may try.

• Make sure the charging ports are clean and free of debris or dirt. If required, wipe them down with a soft cloth.
• Make sure the USB cord is in good working order. To test if it's working properly, try using alternative USB cords (if available).
• Other appliances should not be plugged into the same power source/outlet that you use to charge your iPhone. You might also try to utilize any other accessible functional power outlets.