Chosen Solution
I have iPhone 7 Plus, a week ago it had battery replaced. I noticed that battery is not working as long as the original battery was working brand new. Today I was snapchatting with my friends and when I turned on the front camera on snap and in the same moment I took the image (with flash) my phone just went black, no vibrating when home button pressed and no sounds. I put phone on charger but nothing happends. Edit: I put my phone on charger and nothing happends, phone is cold and doesn’t get any warmer. Tried to turn it on, nothing happends.
Put back in your old original battery and look if it boot up your phone.
