The Asus Zenfone Flash Tool is no official Software, furthermore it looks like this tool is using fastboot (which usually works on previously unlocked bootloader only)
fastboot.exe download platform-tools and open
cmd.exe. navigate to
platform-tools folder with
cd now you can type
if bootloader is already unlocked, you can also wipe cache partition and see if this fixes your boot problem
fastboot format:ext4 cache
you can also boot into recovery from fastboot and then install firmware update.zip. this should even work from TWRP as long as you don't flash recovery.
do NOT allow modifications of system. just wipe cache partition. try to reboot into system from menu. if still not booting, install firmware update.zip
fastboot boot C:\platform-tools\twrp-3.2.3-zenfone3-20180806.img
for locked bootloader you can download Factory_Phone-userdebug.raw emmc image which contains GPT partition table and all partitions. (from linux it is possible to loop-mount this image with kpartx and split into partitions, but this is out of scope)
WARNING: all data lost
this will flash the entire device, be aware this deletes all your personal data. make sure this is the right phone model.
it seems no flash tool is needed, it is maybe working from fastboot directly.
connect usb cable in fastboot mode and just run
Qualcomm Devices usually can be flashed from EDL mode with QPST.
found a site with some Qualcomm EDL Programmers maybe one of this works for your device
for EDL mode install Qualcomm HS-USB QDLoader 9008 Driver
for EDL mode you need to find Test Point
The following is just an example to illustrate the process and not valid instructions
For further documentation refer to alephsecurity there you can learn how to flash devinfo which unlocks bootloader and gives availbilitiy to flash custom recovery TWRP
basically you need the following files (most of them are included in QPST)
the xml file has instructions for flashing partition, for example TWRP (not the right size/offset)
<?xml version="1.0" ?>
<program SECTOR_SIZE_IN_BYTES="512" file_sector_offset="0" filename="recovery.img" label="recovery" num_partition_sectors="131072" physical_partition_number="0" size_in_KB="65536.0" sparse="false" start_byte_hex="0x1c200000" start_sector="921600" />
QSaharaServer.exe is used to initialize firehose with on the already to COM port connected device in EDL mode
QSaharaServer.exe -p \\.\COM10 -s 13:prog_emmc_firehose_8953.mbn -b tmp\"
fh_loader.exe is responsible for flashing the instructions from xml file
fh_loader.exe --search_path=tmp --port=\\.\COM10 --sendxml=twrp.xml"