Is the phone currently or can it boot to the Huawei logo/Fastboot screen ?
Release the buttons when you see the Huawei/Honor logo. The phone will automatically detect the update.app file and begin the official installation upgrade. Critical Safety Tips for Kirin 710 Flashing hisilicon kirin 710 flash tool
: Writing raw factory software ( .xml or split factory images) directly to the flash storage to resurrect dead devices that show no display indicators. Is the phone currently or can it boot