I see someone here have problems with bricked phone. It just keeps restarting and you cant even turn it off.
The problem is here that UPDATE never ended to 100% and software successfully changed boot.img to the new one
but with old system on the phone.
Its even worse if you have TWRP recovery installed before update then it will brick the phone too.
Allways install stock recovery on current rom before update firmware.
Ok i will start now with this guide because i had same problem and fixed it by myself.
I will not put any links to downloads find them self GOOGLE is your friend
First of all if you were on B200 5.0.1 version of android then you need B170 firmware to extract boot.img and recovery.img from
the UPDATE.APP file
For that you need a software called Huawei Firmware Extractor
Download it and install
Now you need even ADB/FASTBOOT on the computer. If you dont have download and install. Install even drivers for the phone
Now Open the Huawei Extractor and add the UPDATE.APP file.
Now you will see alot of files below
Now mark the boot.img system.img and recovery.img and extract them to the desktop of your PC
Now copy those files to the ADB/FASTBOOT folder.
You phone i still under the bootloop and you need to get it into FASTBOOT mode. Only way to do it is to plug in USB cable to the phone.
Now as soon the phone reboots by itself hold Power and Vol down button until you see white screen and fastboot mode
Now go to the ADB/FASTBOOT folder where you copyed files and hold shift and press right mouse button to get "Open command window here"
So you will be in fastboot and you will see C:/ADB that is right directory
Now start with fastboot erase cache
Then write fastboot flash boot boot.img and hit enter
When done do following fastboot flash recovery recovery.img and hit enter
You can if you want even try to flash system.img by writing fastboot flash system system.img or fastboot flash system.img dont remember that combination
but try and see wich works.
Now write fastboot rebootand phone will reboot . If you still have bootloop then as soon phone goes black then Hold Vol+up and Power until you see recovery.
Over there make factory reset and cache and then reboot.
If you still cant boot into recovery then you need to get Firmware B170 and put it on you SD card in DLOAD folder
to flash it from scratch. Same here is that you need to have USB plugged in in order to get to EMUI flash mode or it will wont work.
Remember that you only need UPDATE.APP in the DLOAD folder from B170 firmware.
I know my English sucks but im trying to help...