Why is my phone not turning on?

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.