vivo smart 3 won't stay on

I just got a vivo smart 3 brand new.

but when I unplug the usb charger, the vivo smart 3 dies.

it only comes on when it is plugged in.

everything is synced, and i have the app on my phone, everything is connected.

but the power just dies when it is not plugged in.
Does anyone else have this problem??????