Why does my iPhone 6s Plus keeps turning on and off by itself and it won't charge.

mc177 Said:

“Question: Why does my iPhone 6s Plus keeps turning on and off by itself and it won't charge.”

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Get a New Battery or to just Upgrade:

If my above reply does not help, then your battery is dying out. So, this seems like a good reason to get a new, more recent iPhone. Elsewise, just get a new battery. Your local retailer may have one, and may be able to replace the battery.

mc177 Said:

“Question: Why does my iPhone 6s Plus keeps turning on and off by itself and it won't charge.”

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A Few Apple Support Sites that May Help:

• iPhone Battery and Performance

• Charge and monitor the iPhone battery

• About the battery usage on your iPhone

• About Optimized Battery Charging on your iPhone

• If you see "Your iPhone battery may need to be serviced"

• Use Low Power Mode to save battery life on your iPhone