I didnt have enough time yesterday to post my steps, but here they are anyway:
Download these files before starting:
1. ZTE handset USB driver and Qualcomm EDL 9008/USB driver (
https://androidfilehost.com/?fid=11410963190603913612
2. Latest version of the MultiDL Tool (
https://androidfilehost.com/?fid=11410932744536984126
3. MiFlash (may not be the latest version but it has always worked for me,
https://build.nethunter.com/misc/axon7/MiFlashSetup.msi
4. Axon 7 EDL Tool (optional, but sometimes works better than MiFlash and has more features, refer to the forum thread for details on how to use it,
https://forum.xda-developers.com/attachment.php?attachmentid=4682066&d=1546889147
For a clean start, uninstall the DFU MultiDL Tool and MiFlash from Windows Control Panel. Open Device Management (search for devmgmt.msc from start menu, or hit Windows key+R, type it in, press Enter). Enable the viewing of hidden devices, open every category and uninstall every driver that mentions ZTE, Qualcomm 9008 (not exact wording but it will be obvious). Be especially sure to check under the Unknown/Other categories, as well as USB and Ports categories. If a checkbox appears asking to remove the driver, click it, then OK.
I'm not sure if the next step is absolutely necessary, but I sometimes didnt get driver install prompts if DSE is enabled. Modern Windows 64 bit OSes since Vista have Driver Signature Enforcement enabled by default, which can prevent a driver from installing. All provided driver files should be signed but it's better to get this right the first time. So:
Open a command prompt as admin (type cmd in Start menu, right click, run as admin), type the following, reboot again:
bcdedit /set TESTSIGNING ON
Afer you have rebooted you will notice a watermark in the lower left of your desktop. It is insecure to run Windows with DSE always off, so when done with all my steps you should type the above command again, but change ON to OFF and reboot.
Next steps:
1. Extract
@raystef66's A2017G_Driver.zip, it says G but it will work on A2017/A2017U models too.
2. In the extracted Windows folder, run Autorun.exe as admin (ZTE Handset driver).
3. In the other extracted folder you will find 3 files ending in inf, right click each of them and click Install. Dont worry about the other subfolders. This is the Qualcomm EDL 9008 EDL/USB driver.
4. Install MiFlash
5. Install ZTE MultiDL Tool.
Do the above steps *IN THE ORDER* I have listed them. And dont plug phone into PC until you have done all the steps.
Now you are ready to use the DFU MultiDL Tool. Use the pics here as a visual reference (
https://forum.xda-developers.com/showpost.php?p=77926571&postcount=35
Now, make sure phone is off. Hold volume up, volume down, then power in that order, but keep all buttons held down. You should feel a vibration, maybe not. If you see a solid red light/LED in upper left corner of phone screen, this is DFU mode. Red light that either blinks or turns off is EDL, you can just skip the DFU MultiDL tool and go straight to flashing with MiFlash or A7 EDL Tool. You can also use Device Management as an indicator for which mode the phone is in.
Plug in device to PC, open the DFU tool. Find the Port Config button, then click Port Manager. If your phone isnt listed as a COM diag port then this probably wont work. Under the line where the COM button is listed, remember the USB number. Close Port Manager, click line 1, then select the USB number you saw. Then click OK. You should hear a USB disconnect sound on PC, and the red light should turn off. This means you are in EDL mode (or should be). Close the DFU tool and open either MiFlash or the EDL Tool batch file and flash. Be sure not to have more than one of these programs open at once, since they may be in conflict by trying to access the phone simultaneously. While EDL flashing or or using the EDL tool, open the Task Manager and kill any adb.exe processes. The EDL Tool can use ADB to switch to EDL, but it but it shouldnt be running during the actual flashing process.
Now you can flash with the other tools I listed (preferably a full stock ROM EDL zip of your choice for a fresh start, then you can bootloader unlock, flash TWRP/custom ROM/etc later). If MiFlash gives an error, or the EDL Tool gets stuck on loading the firehose file then you are probably not in EDL. Try disconnecting/reconnecting phone to PC. If that doesnt work then do the steps with the DFU Tool again. If still not working then you can put the phone in DFU mode and let the red light drain the battery completely. Then charge for a few mins (at a minumum, battery charging screen may not appear, just use your judgement). This may take hours depending on how much charge the phone has. Bottom line is you must get to EDL or you're going nowhere fast.
Once you are in EDL then you can flash with the normal tools and unbrick. DFU MultiDL Tool can also EDL flash files to the device, but I have never gotten it to work (didnt try too hard). A user has earlier mentioned that running the tool in Windows 7 compatibility mode may allow EDL flashing to function properly, if you are using Win8/8.1/10. I will test more later but for now just use the other tools.
Another thing, be sure to run all tools/installers as admin. Use a good cable. And use a USB 2.0 port if available (not an option for me since my laptop has only USB3/USB C).
If you still cant get these steps to work in a real Windows install, it is possible there are deeper conflicts somewhere (usually installed drivers/programs) then you can try installing Win10 64 bit in a VMware Workstation (paid software but has 30 day trial)/VirtualBox (free) virtual machine. Then do my steps. Win7 will also work (not recommended if you have USB3 ports and no USB2). In the VM program you can share (pass through) a USB port from the host OS to the guest OS, set config to either USB2 or USB3 in VMware/VirtualBox, depending on your PC. Microsoft hosts free trial downloads of Windows which dont need to be activated immediately, those will suffice, so no need to pay or pirate. I use Linux as my main OS, I find VMs to be useful for flashing phones.
Absolute worst case is that none of this works, then you can either dissassemble the phone and short circuit the test point using
@Choose an username...'s DFU unbrick guide (never did this myself, dont want to damage phone). Or you can RMA the phone to ZTE if the warranty is still valid. I have RMAed to them twice in a year and dont want to do it again so I'm posting this guide in the hope that someone will find it useful. And because I feel that the steps listed by others are incomplete, dont list and give links to all required tools, or provide a proper step order to follow.
@raystef66: If you find this post useful then maybe you can link to it in the first post as a starter reference.
, ofc crDroid can indeed be flashed on treble phones . And it's indeed fully customed for A7. 
