Hi! Sorry to hear it. Have you tried a soft reset yet? If your phone is unresponsive, you can reboot it phone by pressing the volume up key and the power button simultaneously for about 15 seconds (or until your phone vibrates). It should then restart momentarily. This is a safe and quick way to reboot your device without losing or erasing any data.
If this doesn't work, it might be worth it to take your phone to a care center near you.
Hope you get to enjoy your phone without any issues soon!
Yes I had this common enough problem with my Nokia 3. However, since upgrading to Android Oreo beta the problem has not occurred again. Prior to upgrading from 7.1.1, I was getting the Nokia 3 powering itself off at least twice a day and always when I plugged in the USB charger cable regardless of the actual battery charge.
I used the OTA upgrade from 7.1.1 to Oreo 8.0 beta 15 days ago and have been unable to reproduce the problem since then.