[ZTE Axon 10 Pro ROMs, Kernels, Recoveries, & Other] bobthenormal:
Well I really am a glutton for punishment - I'm back into EDL stuck hell! I was trying to flash Unjustified's LOS... 17 flat out didn't work, so I tried 16 and it seemed to work... but when went to reboot to install gapps I was stuck in EDL. I've tried a TON of combinations of flashing through the EDL tool and nothing has worked. Really rough.

I don't know why this keeps happening to me, but I have a guess for that - I have done a lot of unlocking followed by reformatting which of course leaves the system image in an uninitialized state. And I haven't bothered to set it up - as in, go through the google setup and start the OS. I didn't think I should need to... but my guess now is that maybe when that happens the system SETTINGS get reset too - namely the toggle for unlocked bootloader. So then I have a locked system setting on top of an unlocked bootloader. Maybe that has been causing my EDL run-ins... which leads me into my next theory...

I didn't get around to testing those three files. to see which one caused the EDL.. but now I think it's more complicated than just that. My running hypothesis is that it's a combination of getting several things lined up - so the boot, bootloader, and system are not in conflict - and maybe other important partitions too but I don't know enough about it to guess which ones. Which especially has me worried that you can't use the EDL tool to restore many of the "all" backup partitions - in this case maybe one of those got screwed up by the LOS install and I could fix it if I could restore that way. I've started to pick through the EDL tool programming to see if I can't figure out how to extend it to do the "all" restore. Not there yet.

My guess is, in general, that the phone starts loading the bootloader but finds a conflict in the state of the phone (lock/unlock) or in one of these other partitions (?) and emergency halts the entire system into EDL. And if you can get past the BL halt -> EDL, and it bootloops it's because of a conflict of the boot sectors with all that - any easy fix by replacing the boot with an -appropriate- boot image to match everything up. Again, just a guess from me.. and I'm very unknowledgeable about the hardware/firmware in phones despite having a good background in understanding these things generally (engineering), so who knows. I just have to keep trying some approach =(

Anyway, here's the post for fixing the bootloop if you can get out of EDL: https://xdaforums.com/showpost.php?p=82857993&postcount=162

Hoping that [MENTION=4911249]Unjustified Dev[/MENTION] gets some time to chime in with anything that might be helpful. The go-to solution for my situation in other threads that he suggests would appear to be a factory firmware install using a tool like MiFlash or QPST but I haven't been able to get either to work (as others haven't - these software packages seem extremely touchy about drivers, windows versions, etc.). I always end up with the same error.. something about unable to read, 0 bytes read or something. Googling suggests it's again more of a driver/communication issue than a problem with the firmware backup I'm using... but I can't be sure. I don't have a win7 box to try them on.

I have no idea how the firmware backups are different from these EDL backups - they looks very similar except for some extra bin's and XML files... not sure if the XML's are just instructions of which files to restore and which partitions to install them to, or if they are more complicated like specifying sector locations, etc. Hard to troubleshoot when I know so little about it! lol

I do have one question for [MENTION=4911249]Unjustified Dev[/MENTION] or anyone else who knows - in trying to use MiFlash the two types of firmware backups I have are completely unrecognized by it. Is there something I can do to make them recognized, or do I need a different format of ROM entirely?

I have these files, found various places in these threads - "GEN_NA_P855A03V1.0.0B11_DL" and "A2020U_B12_FULL_EDL_FIRMWARE". 1st one is supposed to be a factory ROM install. 2nd one is someone's (sorry for forgetting who) EDL tool backup. Neither one works for me using them to do a "full" restore in the EDL tool. And neither one can use the "flash", they're always marked as "sparse".