[Honor 6X Guides, News, & Discussion] RedSkull23:
Yesterday i was upgrading my phone from B368 to B369, and wronging by impatience, i decided to shut down while my phone was apparently blocked on the NAG screen (your phone has been unlocked and can't be trusted screen at startup); in truth, it wasn't blocked but it was just applying updates during reboot and he was tooking some more time than usual... The result? My model number changed from BLN-L21 to generic_a15, and so apps like camera was keeping crashing and became not usable.

After had restored a TWRP backup made before updating, and so on B368 build, i ended up with BLN-L21C432B369 as build number, but without having the latest security patch and latest improvements. In poor words, the B369 build was shown even if i was on B368 at all, and so system update wasn't detecting any other updates since that i was apparently on the latest build.

[DISCLAIMER: don't point your finger on me if you end up with your phone exploding, emitting toxic spores or radiations, please. I'm just putting this simple guide here as a way to possibly solve your issue, but i can't know if it'll works on EVERY different model, variant or kind of issue; in mine case it worked like a charm, but BE CAREFUL. I'm not responsable for anything]

What i did for fix this issue was very, very simple, much simpler than what i thought to face; i just started combing here and there in the various root folders thanks to a root explorer (i used MiX, for example) containing the various local.prop and build.prop files scattered around the system folders, until i found the right one to tweak with. The path to follow is very simple: you just need to browse to

root/version/special cust/BLN-L21/hw/eu/prop/local.prop

(note that the path will obviously change if you own a BLN-L22, a BLL-L22, ecc. but the road will be always the same - you'll find other folders name after special cust, BLL-L22 other than BLN-L21, china instead of eu for example, but often it's always straight to the last folder that finally contains the local.prop file)

and once there, with the help of a text editor, correct all the errors that you'll find mismatching with your actual build number. The voices that i had to correct are circled in orange in the picture that i attached here below, (note: the picture shows voices already fixed) and there was four of them to adjust;

ro.build.display.id=BLN-L21C432[B][COLOR="Red"]B369[/COLOR][/B]
ro.build.version.incremental=C432[B][COLOR="red"]B369[/COLOR][/B]
ro.build.description=BLN-L21 -user 7.0 HONORBLN-L21 C432[B][COLOR="red"]B369[/COLOR][/B] release-keys
ro.build.fingerprint=HONOR/BLN-L21/HWBLN-H:7.0/HONORBLN-L21/C432[B][COLOR="red"]B369[/COLOR][/B]:user/release-keys

since that in this case i was on B368 other than B369, as shown by phone info in settings menu, i just tried to modify that number with an 8 instead of a 9, gave the phone a reboot and... It's done!

**Method Update!**
[MENTION=4856002]BakedOnSomeSour[/MENTION] pointed out a way to

definitely

correct the build number, permanently and safer than my method!

To do this, flash the version.img matching your firmware build, an image that you can extract from the UPDATE.APP of each update.zip package through TWRP (flash the file as image of course, by selecting the dedicated option in TWRP menu). In this way, the build number will be definitely fixed!

Thanks to BakedOnSomeSour for finding a faster and more efficient method.​

Be aware, and backup before doing this or everything you're dubious about.

Cheers