Those who have a relative young iPhone 6s that can no longer be switched on can be lucky: Apple has launched a repair program for the iPhone classic.
The iPhone 6s has been distributed by Apple for a very long time and the last ones being produces seem to have a hardware bug: a component of the power supply system can be faulty and the units can’t be switched on anymore. Apple will then repair them free of charge. Important: this repair program is limited to devices produced between October 2018 and August 2019, for older models this offer does not apply.
If you have such a device that cannot be switched on anymore, you can enter the serial number of your device on Apple’s support page and if necessary register for a repair right away.