[Miscellaneous Android Development] :
I tried to install this with adb sideload in TWRP. Everything seemed to go smoothly, wiped all partitions, Dalvik, System, cache, Data, Internal Storage. However when when I went to quit TWRP after the sideload to reboot into the OS I saw "No OS Installed!"

On a side note I assume it is normal to see?

Red State
Your device has failed verification and may not work properly.
Your device will boot in 5 seconds.

I saw the LineageOS logo spin around and it appeared to be doing something, so I left it for about 6 hours. Nothing had actually happened when I got back. I produced logs with logcat if that's any help. What could have gone wrong? I tried DotOS and it did exactly the same thing.

Logcat output

Password:

>XO;e5?A#F:n?<7wWuWP

I backed my whole ROM up with this [Tutorial] How to use Wwr_MTK + SP Flash tool to backup Mediatek rom prior to commencing any flashing or installation of TWRP. I backed up all areas of the memory except for cache and userdata. I used SP Flash tool to extract the 14.5GB memory dump and then Wwr_MTK to split it all up into these areas.

16777216 boot.img
524288 efuse
10485760 expdb
16777216 flashinfo
1048576 frp
8388608 keystore
524288 lk.bin
8388608 logo.bin
38273024 metadata
11490 MT6735_Android_scatter.txt
33554432 nvdata
5242880 nvram
2097152 oemkeystore
524288 para
524288 pgpt
127356 preloader_wt98736b32_da1.bin
3145728 proinfo
10485760 protect1
10485760 protect2
16777216 recovery.img
524288 seccfg
6291456 secro.bin
524288 sgpt
3221225472 system.img
5242880 trustzone1.bin
5242880 trustzone2.bin

Was this the tool you used? I had a look at [Tool][Windows/Linux][Dec 13 2017] Android Flashable Zip Creator v5.0 Alpha to create my own modem firmware package.

I suspect this is what was causing my problems with both LineageOS and DotOS not booting. (Just saw logo forever and occasionally simcard symbol with cross through it would appear). This one is for the XT1758 NRD90M.014 (Retail Asia Pacific Region).

ca730c4d81c1547d9b1db8adea4836a78bd97537759c0ffd1f1105bd5d9f0961 modem_namath_57/customize/aroma_0/Project_modem_namath_57/Type_custom_Loc_+system+vendor+firmware_Perm_1000-1000-0644/Group_Modem/modem_1_lwg_n.img
2ee70df8190087d8ab848b0ced49936c5750b2fce9d29c31f2ae21a3c33c6f79 modem_namath_58/customize/aroma_0/Project_modem_namath_58/Type_custom_Loc_+system+vendor+firmware_Perm_1000-1000-0644/Group_Modem/modem_1_lwg_n.img

As you can see the SHA256 does differ from the XT1757. To create the zip file I just imported the modem_namath_57.zip I deleted modem_1_lwg_n.img and added my own.

I found when I right clicked on the project and did Custom Group I had trouble setting an owner. (This might be because of my HiDPI screen using Adwaita theme on Ubuntu). The FlashableZipCreator tool kept saying that "owner cannot be empty (1000 may be?)". I couldn't see how to set that, is there a field on that screen to set that?

I then went into File > Preferences and made sure to set Zip Options to "Zip Type".

After using adb to sideload LineageOS to my phone I also sideloaded my new modem modem_namath_58.zip My phone was then in a bootloop. Same for DotOS. Here is the log file from logcat after I did it with LineageOS logcat-lineageos-crashwithmodem-14.1-20180701.zip. Unlike previously where it just was 'forever booting' with a black screen and the occasional time that sim card logo would pop up in the top right-hand corner by where the clock and battery status sit.

Password:

>XO;e5?A#F:n?<7wWuWP

To those who are skimming this don't blindly use these files until we find out what is wrong.

modem_namath_58.zip

I also tried that however I was still facing the same issues.

modem_namath_58_all.zip

Password:

>XO;e5?A#F:n?<7wWuWP

I also decided to put lineage-14.1-20171223_034051-UNOFFICIAL-namath.zip and addonsu-14.1-arm-signed.zip on my external sdcard, I guess you could copy them to Internal Storage too. That avoided the "No OS Installed!" error I was getting even though adb sideload should work. However the screen still was showing the boot logo, and then after a while going black, even with modem_1_lwg_n.img installed into /system/vendor/firmware and chmodded to 0644 ie -rw-r--r--