[Q] Modify apk - Set minSdkVersion - Android Q&A, Help & Troubleshooting

Hey guys,
after hours I spent with this Im finally at the point where Ive to admit, that I've no clue how to get that job done.
Im trying to modify following Spotify APK: Spotify Music – for Android TV 1.0.0 found on apkdot.com/apk/spotify-ltd/spotify-music-for-android-tv/spotify-music-for-android-tv-1-0-0 (sorry, cant use url bb codes because thats my first post...)
What I want to achive is, to set the minimum sdk version to 19. (Android 4.4).
I tried several ways, which in general should all do the same (APK Studio / apktool / ...).
Because at the end the results were the same Im just writing the apktool steps I made.
Decompile the app: apktool.bat d com.spotify.tv.android_1.0.0.apk
Modify the AndroidManifest.xml (inserted this line): <uses-sdk android:minSdkVersion="19"/>
Recompile it: apktool.bat b com.spotify.tv.android_1.0.0
After that i signed it and installed it on the device. At least I can say, it installed without any parsing errors. When I want to start it though, it just crashes without any message. Opened up logcat and saw this a NoClassDefFound-Exception:
Code:
E/AndroidRuntime( 5660): FATAL EXCEPTION: main
E/AndroidRuntime( 5660): Process: com.spotify.tv.android, PID: 5660
E/AndroidRuntime( 5660): java.lang.NoClassDefFoundError: d
E/AndroidRuntime( 5660): at com.spotify.tv.android.recommendations.RecommendationsManager.a(Unknown Source)
E/AndroidRuntime( 5660): at com.spotify.tv.android.recommendations.RecommendationsManager.a(Unknown Source)
E/AndroidRuntime( 5660): at com.spotify.tv.android.service.SpotifyTVService.a(Unknown Source)
E/AndroidRuntime( 5660): at com.spotify.tv.android.service.SpotifyTVService.b(Unknown Source)
E/AndroidRuntime( 5660): at com.spotify.tv.android.service.SpotifyTVService.onStartCommand(Unknown Source)
E/AndroidRuntime( 5660): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2702)
E/AndroidRuntime( 5660): at android.app.ActivityThread.access$2100(ActivityThread.java:135)
E/AndroidRuntime( 5660): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293)
E/AndroidRuntime( 5660): at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime( 5660): at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime( 5660): at android.app.ActivityThread.main(ActivityThread.java:5017)
E/AndroidRuntime( 5660): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 5660): at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime( 5660): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
E/AndroidRuntime( 5660): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:603)
E/AndroidRuntime( 5660): at dalvik.system.NativeStart.main(Native Method)
W/ActivityManager( 484): Force finishing activity com.spotify.tv.android/.SpotifyTVActivity
D/dalvikvm( 5660): GC_CONCURRENT freed 555K, 43% free 2659K/4648K, paused 0ms+1ms, total 10ms
I/WindowManager( 484): Screenshot max retries 4 of Token{41cfd018 ActivityRecord{41b700b0 u0 com.spotify.tv.android/.SpotifyTVActivity t28 f}} appWin=Window{41d3dc28 u0 Starting com.spotify.tv.android} drawState=4
W/WindowManager( 484): Screenshot failure taking screenshot for (1920x1080) to layer 21025
I/Process ( 5660): Sending signal. PID: 5660 SIG: 9
V/AudioFlinger( 113): remove track (4097) and delete from mixer
D/ActivityManager( 484): send app_CRASH broadcast, packageName:com.spotify.tv.android
I/ActivityManager( 484): Process com.spotify.tv.android (pid 5660) has died.
I/WindowState( 484): WIN DEATH: Window{4215d8e8 u0 com.spotify.tv.android/com.spotify.tv.android.SpotifyTVActivity}
W/ContextImpl( 484): Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:1162 com.android.server.am.ActivityManagerService.onVideoPlayerCrashed:3689 com.android.server.am.ActivityManagerService.handleAppDiedLocked:3719 com.android.server.am.ActivityManagerService.appDiedLocked:3857 com.android.server.am.ActivityManagerService$AppDeathRecipient.binderDied:1043
Ive no clue how to fix it. Even if there is a way to fix it. Hope you guys can help me .
Termi
PS: Ive Spotify Premium