New battery....white screen and then dead

I changed the battery in an old iphone 6, initially I had the white screen with the Apple logo, tried holding the power and home buttons down but that did nothing.

The person whose phone it is said it was probably because the battery was yet to be fully charged and plugged it in overnight. Now the phone is won't power up at all, no white screen and it's not recognised when plugging into a computer?

Has the phone reached the end of its life?

Many thanks