If your iPhone 6s refuses to turn on, it's probably not because of anything you did. Instead, the problem may lie within the iPhone itself.
That's the word from Apple, which posted a support document today (Oct. 4) to announce a repair program for the iPhone 6s and 6s Plus. Some of those phones built between October 2018 and August 2019 aren't powering on, with Apple blaming the problem on a failed component. Only devices within a limited range of serial numbers are affected by the issue, Apple says.
If your iPhone 6s or 6s Plus has trouble starting up, you can head to Apple's website to plug in your serial number and find out if you're eligible for a free repair. Even if that trouble hasn't flared up yet on your device, it might be a good idea to check anyhow. If you need a repair, you'll have the option to schedule an appointment at an Apple Store, find an authorized Apple service provider or mail in your phone for repair.
Unless you bought your iPhone 6s or 6s Plus very recently, though, you're not likely to be affected by the issue Apple's highlighting here. After all, Apple dropped the iPhone 6s models from its lineup last year when it introduced the iPhone XS, XS Max and XR. Apple did continue to offer those phones in some areas outside the U.S., though.
There's still some life left in that iPhone 6s, anyhow. iOS 13, released last month by Apple, runs on the iPhone 6s and 6s Plus, so your older phone still gets access to features like Dark Mode and the improved Maps and Photos apps.