[Xiaomi Redmi 2 ROMs, Kernels, Recoveries, & Other ] PolesApart:
[MENTION=5432026]nicknitewolf[/MENTION] I think this may be the soft bootloop spot:

06:56:59.233 11146 11185 E AndroidRuntime: *** FATAL EXCEPTION IN SYSTEM PROCESS: android.display
06-17 06:56:59.233 11146 11185 E AndroidRuntime: java.lang.RuntimeException: Failed to boot service org.lineageos.platform.internal.display.LiveDisplayService: onBootPhase threw an exception during phase 1000
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.SystemServiceManager.startBootPhase(SystemServiceManager.java:162)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.am.ActivityManagerService.finishBooting(ActivityManagerService.java:5251)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.am.ActivityManagerService.bootAnimationComplete(ActivityManagerService.java:5306)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.wm.WindowManagerService.performEnableScreen(WindowManagerService.java:3353)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.wm.WindowManagerService.access$1100(WindowManagerService.java:287)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.wm.WindowManagerService$H.handleMessage(WindowManagerService.java:4886)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at android.os.Handler.dispatchMessage(Handler.java:107)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at android.os.Looper.loop(Looper.java:214)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at android.os.HandlerThread.run(HandlerThread.java:67)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.ServiceThread.run(ServiceThread.java:44)
06-17 06:56:59.233 11146 11185 E AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object[] java.util.Collection.toArray()' on a null object reference
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at java.util.ArrayList.addAll(ArrayList.java:588)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at org.lineageos.platform.internal.display.PictureAdjustmentController.<init>(PictureAdjustmentController.java:54)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at org.lineageos.platform.internal.display.LiveDisplayService.onBootPhase(LiveDisplayService.java:164)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	at com.android.server.SystemServiceManager.startBootPhase(SystemServiceManager.java:159)
06-17 06:56:59.233 11146 11185 E AndroidRuntime:	... 9 more
06-17 06:56:59.234 11146 11185 I am_crash: [11146,0,system_server,-1,java.lang.NullPointerException,Attempt to invoke interface method 'java.lang.Object[] java.util.Collection.toArray()' on a null object reference,ArrayList.java,588]

The full logs are attached.

EDIT: It seems that we have two problems: something makes the system soft crashes. I don't know what. The logcat is restarted when this happen so my log didn't caught there, would have to let it running and wait for it to happen.

After that, then we have the bootloop problem, which is reproductible i.e. by adb root && adb shell "stop ; start"

EDIT 2: I did this by hand (unsquashfs on vendor / mksquashfs / reflash):https://review.lineageos.org/c/LineageOS/android_device_huawei_kiwi/+/255422

and the stop ; start sequence no longer bootloops :laugh:

But there's still the crash hunt for whatever leads to the "stop" equivalente scenario in the first place.