Can't downgrade KIW 21 from B370 to B350 - Honor 5X Questions & Answers

Can't downgrade my Honor 5x from B370 to B350, which is obviousely required before flashing Lineage OS.
- A lot of Guides write that the downgrade should be performed with the Android Update App, then choosing "local update". This doesn't work, because this "local update" menu option is no longer available on B370 Firmware.
- Other Guides write to put the "update.app" file with the old B350 firmware in a dload folder on the SD card, then to restart the phone by pressing both volume keys and power key at the same time. When I'm doing that, the package is verified, then the installation starts, stuck for about 2 minutes at 5%, then the phone reboots without any message, and nothing happened. The Honor 5x is still on B370.
Any advice? Have tried different B350 Packages from different sites. Has anyone a link to a B350 (or to another old Firmware that works for a Linage OS installation) that is proved to work for downgrading B370 on KIW 21? Thank you all in advance for any help.
Franz

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franzschenk said:
Can't downgrade my Honor 5x from B370 to B350, which is obviousely required before flashing Lineage OS.
- A lot of Guides write that the downgrade should be performed with the Android Update App, then choosing "local update". This doesn't work, because this "local update" menu option is no longer available on B370 Firmware.
- Other Guides write to put the "update.app" file with the old B350 firmware in a dload folder on the SD card, then to restart the phone by pressing both volume keys and power key at the same time. When I'm doing that, the package is verified, then the installation starts, stuck for about 2 minutes at 5%, then the phone reboots without any message, and nothing happened. The Honor 5x is still on B370.
Any advice? Have tried different B350 Packages from different sites. Has anyone a link to a B350 (or to another old Firmware that works for a Linage OS installation) that is proved to work for downgrading B370 on KIW 21? Thank you all in advance for any help.
Franz
Click to expand...
Click to collapse
Try this maybe
Someone posted patch to use customrom without downgrade
In slimrom thread in dev thread

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"Someone posted patch" is very unspecific. How should I find that patch? Thank you in advance for any guidance.

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franzschenk said:
"Someone posted patch" is very unspecific. How should I find that patch? Thank you in advance for any guidance.
Click to expand...
Click to collapse
Its written, go to most recent slim ROM thread in dev thread.
Not my fault if xda app do not handle copy link post.
Édit:
https://www.google.fr/search?dcr=0&...HUxrzZAhXJYVAKHbCnCbEQBQgYKAA&biw=400&bih=593
Last post

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Here

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Thank You!
So what is the recommended upgrade procedure for installing Lineage OS on Honor 5x with Stock FW B370?
1. Flash Lineage OS over B370
2. Flash this Patch
or is it the other way round?
It's disappointing that there is not anymore any guide that works. It's impossible to flash any older Honor 5x stock firmware version. It doesn't work with the Honor update program (local update option is no longer available), it doesn't work with power+Vol-Up+Vol-Down (phone reboots at 5% without installing anything), and it's also not possible to flash a Honor firmware zip with TWRP (Error 7).
What's intresting is that only Lineage OS warns that a VoLTE FW like B370 has to be downgraded before installing Lineage OS. All XDA developer sections for all the other custom ROMs don't mention that a VoLTE FW has to be downgraded before installing the custom ROM.
- Has anybody successfully installed a custom ROM on a Honor 5x without downgrading the VoLTE FW before?
- Is this downgrade only required for installing Lineage OS, or is it also required or recommended for installing any other custom ROM?
Franz

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franzschenk said:
Thank You!
So what is the recommended upgrade procedure for installing Lineage OS on Honor 5x with Stock FW B370?
1. Flash Lineage OS over B370
2. Flash this Patch
What's intresting is that only Lineage OS warns that a VoLTE FW like B370 has to be downgraded before installing Lineage OS. All XDA developer sections for all the other custom ROMs don't mention that a VoLTE FW has to be downgraded before installing the custom ROM.
- Has anybody successfully installed a custom ROM on a Honor 5x without downgrading the VoLTE FW before?
Franz
Click to expand...
Click to collapse
×You need twrp first, custom recovery then before anything backup nandroid first then follow normal custom rom flash processus and for volte it seems you need to flash patch after ROM.
If it boot bingo, then flash gapps, magisk whatever you want.
×Los say it but it is known for every ROM
×Seems @lineu94 giving the patch has successfuly used it.
BUT: some say to not flash what you dont know.
Im not responsable for what will happen.
Nore lineu94 giving the patch.
May be PM him to know where he got patch from who......
If it works, give him credits and thank him for useful comment and zip

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Thank you all for your help.
The patch file that you mentioned is for a Honor 8 device.
In XDA Forums, there are at least three threads that describe how to downgrade a Honor 5x from B370 to an older firmware with the three different methods that I have all tried and described here, and not one of them works in my case. My Honor 5x is my primary phone, and my old Galaxy S3 is used by my wife. Since there is not one documented description that works, it's too risky to me to install Lineage OS or any other ROM. I can not take the risk to break my device because I'm using it.
Will stay on B370 stock FW and live with a laggy device and the problems (Exchange Email and Bluetooth) and the missing security patches.
I'm very disappointed from Honor: They promised functional updates for at least two years and security updates even longer. That was one of the main reasons why I have bought the Honor 5x. If Honor wouldn't have lie to their customers, we would have Andoid 8 on our device today. Instead, we have Android 6 with the last security update from March 2017. My next device will be anything other than Honor or Huawei.

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Took the risk to flash Lineage OS after a successful Bachup from TWRP recovery to the SD card., and was finally successsful! But it was a lot of "try and error". What worked for me:
1. Performed factory reset in TWRP, and cleaned dvalik/cache, Then, I flashed Lineage OS, the ZIP file that was mentioned here and open Gapps in this order. Then performed factory reset and clean dvalik/cache.
2. The phone restarted, but landed in some kind of Huawei Recovery. Could restart the phone several times, always landed in Huawei recovery.
3. Rebooted the phone with pressing both volume keys and the power key at the same time. It booted into TWRP recovery.
4. Reflashed Lineage OS and Gapps again without the ZIP file. Performed facory reset again.
And hurra, the Honor x booted in Lineage OS

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franzschenk said:
Took the risk to flash Lineage OS after a successful Bachup from TWRP recovery to the SD card., and was finally successsful! But it was a lot of "try and error". What worked for me:
1. Performed factory reset in TWRP, and cleaned dvalik/cache, Then, I flashed Lineage OS, the ZIP file that was mentioned here and open Gapps in this order. Then performed factory reset and clean dvalik/cache.
2. The phone restarted, but landed in some kind of Huawei Recovery. Could restart the phone several times, always landed in Huawei recovery.
3. Rebooted the phone with pressing both volume keys and the power key at the same time. It booted into TWRP recovery.
4. Reflashed Lineage OS and Gapps again without the ZIP file. Performed facory reset again.
And hurra, the Honor x booted in Lineage OS
Click to expand...
Click to collapse
Does It still working for you? I will try to do this on b360 firmware

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Yes, I'm on Lineage OS and the 5x is still much faster and I like the features.
But there is no more Development for the Honor 5x. According the Honor update promise, our device should be on Oreo today. And Huawei and Honor just stopped releasing unlock codes for the bootloader. It's very important that customers that want to use their device for more than one year stay away from these two brands!

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I also succeeded to install Lineage OS on B360, all what we must to do is install again from TWRP. Everything is working