Huawei P8 Lite 2015 soft-bricked and won't turn on or charge
Easiest answer

https://huaweiflash.com/how-to-flash-huawei-stock-firmware-all-methods/

Basically = press the right buttons to get into bootloader or flash mode.

HiSuite = easiest.

SDCARD FILE MODE = meh...


SP Flash Tool 
is the most difficult - But you essentially leave everything as it is, but select the "scatter file"


That file is in the correct firmware for your phone.