If you mean that the rom won't boot, after you've installed the rom, you need to flash stock recovery and do a factory reset and then boot to rom(after you booted to rom, you fan reflash twrp)I don't know if this is the correct forum... But on my Huawei P8 Lite 2017 I install the TWPR but every ROM I try the phone start with the rom but after few seconds with the screen of the rom reboot. Every image I try, Every Gapps I try (nano/micro) and with or without root. Also if I install from sideload or from sd card , also if I install and do a reboot on every passare or install all in the same moment. ( ROM / GAPPS / ROOT ) or ( ROM / ROOT /GAPPS )
What I have to do to use the phone?