[Fire TV General] Luxferro:
I just tried badserial on the FireTV Sticks initial build (54.1.0.0_user_100211520). It instantly closes... here's logcat:

I/ActivityManager( 445): START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 pkg=net.thejh.badserial cmp=net.thejh.badserial/.MainActivity} from pid 6565
D/dalvikvm( 7600): Late-enabling CheckJNI
I/ActivityManager( 445): Start proc net.thejh.badserial for activity net.thejh.badserial/.MainActivity: pid=7600 uid=10002 gids={50002, 1028}
D/dalvikvm( 445): GC_CONCURRENT freed 792K, 39% free 6348K/10396K, paused 2ms+10ms, total 56ms
D/ProfileManager( 7600): Create ProfileManager instance
I/Activity( 7600): No ActvityExender defined. Proceed with default activity behavior.
I/badserial( 7600): starting... (v3)
I/System.out( 7600): 1 inner classes found
I/System.out( 7600): inner class: android.os.IUserManager.Stub
D/AndroidRuntime( 7600): Shutting down VM
W/dalvikvm( 7600): threadid=1: thread exiting with uncaught exception (group=0x40ef6960)
E/AndroidRuntime( 7600): FATAL EXCEPTION: main
E/AndroidRuntime( 7600): java.lang.RuntimeException: Unable to start activity ComponentInfo{net.thejh.badserial/net.thejh.badserial.MainActivity}: java.lang.RuntimeException: java.lang.NoSuchFieldException: TRANSACTION_setApplicationRestrictions
E/AndroidRuntime( 7600): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2206)
E/AndroidRuntime( 7600): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2258)
E/AndroidRuntime( 7600): at android.app.ActivityThread.access$600(ActivityThread.java:146)
E/AndroidRuntime( 7600): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243)
E/AndroidRuntime( 7600): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 7600): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 7600): at android.app.ActivityThread.main(ActivityThread.java:5129)
E/AndroidRuntime( 7600): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 7600): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 7600): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime( 7600): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime( 7600): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 7600): Caused by: java.lang.RuntimeException: java.lang.NoSuchFieldException: TRANSACTION_setApplicationRestrictions
E/AndroidRuntime( 7600): at net.thejh.badserial.MainActivity.onCreate(MainActivity.java:114)
E/AndroidRuntime( 7600): at android.app.Activity.performCreate(Activity.java:5202)
E/AndroidRuntime( 7600): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1084)
E/AndroidRuntime( 7600): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2170)
E/AndroidRuntime( 7600): ... 11 more
E/AndroidRuntime( 7600): Caused by: java.lang.NoSuchFieldException: TRANSACTION_setApplicationRestrictions
E/AndroidRuntime( 7600): at java.lang.Class.getDeclaredField(Class.java:631)
E/AndroidRuntime( 7600): at net.thejh.badserial.MainActivity.onCreate(MainActivity.java:84)
E/AndroidRuntime( 7600): ... 14 more
D/dalvikvm( 7600): GC_CONCURRENT freed 217K, 12% free 2548K/2868K, paused 1ms+2ms, total 18ms
W/ContextImpl( 445): Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:1353 com.amazon.internal.policy.impl.AmazonPhoneWindowManager$SendTopWindowChanged.run:3297 android.os.Handler.handleCallback:725 android.os.Handler.dispatchMessage:92 android.os.Looper.loop:137
W/ActivityManager( 445): Force finishing activity net.thejh.badserial/.MainActivity
W/ActivityManager( 445): Force finishing activity com.amazon.bueller.settings/.bueller.BuellerApplicationDetailSettingsActivity
I/Process ( 7600): Sending signal. PID: 7600 SIG: 9
I/ActivityManager( 445): Process net.thejh.badserial (pid 7600) has died.
D/dalvikvm( 445): GC_CONCURRENT freed 856K, 38% free 6474K/10396K, paused 9ms+5ms, total 64ms
W/khrn_client( 6565): init_window num_buffers 3 min undequeued buffers 1
W/khrn_client( 6565): init_window window 0x5885ca38, 1920x1080 hintTransform 0x0 do_pre 0
I/AudioManager( 6565): Cleared FLAG_SHOW_UI in setStreamVolume
I/AudioManager( 6565): Cleared FLAG_SHOW_UI in setStreamVolume
I/AwesomePlayer( 114): AwesomePlayer: AWESOME LATENESS 40 ms
W/ContextImpl( 445): Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:1353 com.android.server.am.ActivityManagerService.activityResumed:4556 android.app.ActivityManagerNative.onTransact:420 com.android.server.am.ActivityManagerService.onTransact:1717 android.os.Binder.execTransact:351
I/AwesomePlayer( 114): AwesomePlayer: AWESOME LATENESS 40 ms
W/ContextImpl( 445): Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:1353 com.amazon.internal.policy.impl.AmazonPhoneWindowManager$SendTopWindowChanged.run:3297 android.os.Handler.handleCallback:725 android.os.Handler.dispatchMessage:92 android.os.Looper.loop:137
W/khrn_client( 6565): init_window num_buffers 3 min undequeued buffers 1
W/khrn_client( 6565): init_window window 0x588a3a60, 1920x1080 hintTransform 0x0 do_pre 0
I/AwesomePlayer( 114): AwesomePlayer: AWESOME LATENESS 40 ms
W/bt-btif ( 1090): dm_pm_timer expires
W/bt-btif ( 1090): dm_pm_timer expires 0
W/bt-btif ( 1090): proc dm_pm_timer expires
^C

towelroot was no go as well.