hey bro Do these Simple steps
connect ur phone with Data cable
open terminal and type these commands...
Sudo Adb devices
4.adb boot bootloader
and download twrp img for ur phone and flash it
fastboot oem-unlock
and then
fastboot flash recovery ~/path-to-twrpfile
then
fastboot boot recovery
and then after opning ur recovery u got acess to ur phone Storage.. So make a backup of this thing on PC
then
WIPE ur phone