[Nexus 6P Q&A, Help & Troubleshooting] g_kos:
I have the same problem. Camera an only be used once, after that it starts draining battery in the background.

android 6.0.1

cm 13.0.20151209

Have flushed vendor.img

the output from logcat is attached

gkos@dyno:/$ grep -i cam /tmp/camera

12-19 14:30:55.429 13106 13114 W MessageQueue: at android.hardware.camera2.dispatch.HandlerDispatcher.dispatch(HandlerDispatcher.java:61)

12-19 14:30:55.429 13106 13114 W MessageQueue: at android.hardware.camera2.dispatch.MethodNameInvoker.invoke(MethodNameInvoker.java:88)

12-19 14:30:55.429 13106 13114 W MessageQueue: at android.hardware.camera2.impl.CallbackProxies$SessionStateCallbackProxy.onClosed(CallbackProxies.java:177)

12-19 14:30:55.429 13106 13114 W MessageQueue: at android.hardware.camera2.impl.CameraCaptureSessionImpl.close(CameraCaptureSessionImpl.java:387)

12-19 14:30:55.429 13106 13114 W MessageQueue: at android.hardware.camera2.impl.CameraCaptureSessionImpl.finalize(CameraCaptureSessionImpl.java:598)

12-19 14:30:56.739 927 4473 I ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.android.camera2/com.android.camera.CameraLauncher (has extras)} from uid 10021 on display 0

12-19 14:30:56.774 13106 13106 V CAM_QuickActivity: START onCreate: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.775 13106 13106 V CAM_Profiler: [ 0.000ms][ui] GUARD: CameraActivity.onCreateTasks - START

12-19 14:30:56.775 13106 13106 D CAM_LocationManager: Using legacy location provider.

12-19 14:30:56.780 13106 13106 I CAM_OneCamFtrCnfgCrtr: CaptureModule? true

12-19 14:30:56.781 13106 13106 V CAM_Profiler: [ 6.404ms][ui] GUARD: CameraActivity.onCreateTasks - [ 0.001ms] Glide.setup

12-19 14:30:56.782 13106 13106 V CAM_Profiler: [ 7.037ms][ui] GUARD: CameraActivity.onCreateTasks - [ 0.632ms] OneCameraManager.get

12-19 14:30:56.791 13106 13106 V CAM_Profiler: [ 15.340ms][ui] GUARD: CameraActivity.onCreateTasks - [ 3.049ms] computePictureSizes

12-19 14:30:56.794 13106 14254 I FFMPEG : TITLE : Camera Shutter

12-19 14:30:56.831 13106 13106 I CAM_Profiler: [ 56.159ms][ui] GUARD: CameraActivity.onCreateTasks - [38.727ms] setContentView()

12-19 14:30:56.839 13106 13106 V CAM_Profiler: [ 64.432ms][ui] GUARD: CameraActivity.onCreateTasks - [ 8.273ms] Configure Camera UI

12-19 14:30:56.840 13106 13106 V CAM_CameraController: Closing camera

12-19 14:30:56.841 13106 13122 W CAM2PORT_AndCamAgntImp: Releasing camera without any camera opened.

12-19 14:30:56.841 13106 13106 V CAM_ModulesInfo: EnableCaptureModule = true

12-19 14:30:56.841 13106 13106 V CAM_Profiler: [ 0.000ms][ui] GUARD: new CaptureModule - START

12-19 14:30:56.842 13106 13106 V CAM_Profiler: [ 1.204ms][ui] GUARD: new CaptureModule - STOP

12-19 14:30:56.842 13106 13106 V CAM_SettingsManager: listeners: [com.android.camera.app.CameraAppUI@9f3fc8b]

12-19 14:30:56.850 13106 13106 V CAM_SettingsManager: listeners: [com.android.camera.app.CameraAppUI@9f3fc8b, com.android.camera.ButtonManager@83fdc14]

12-19 14:30:56.850 13106 13106 V CAM_SettingsManager: listeners: [com.android.camera.app.CameraAppUI@9f3fc8b, com.android.camera.ButtonManager@83fdc14, com.android.camera.widget.IndicatorIconController@d1962b2]

12-19 14:30:56.851 13106 13106 V CAM_Profiler: [ 76.125ms][ui] GUARD: CameraActivity.onCreateTasks - [ 8.332ms] Init Current Module UI

12-19 14:30:56.851 13106 13106 V CAM_Profiler: [ 0.000ms][ui] GUARD: CaptureModule.init - START

12-19 14:30:56.851 13106 13106 D CAM_CaptureModule: init UseAutotransformUiLayout = false

12-19 14:30:56.852 13106 13106 D CAM_Camera2OneCamMgr: Getting First BACK Camera

12-19 14:30:56.856 13106 13106 V CAM_Profiler: [ 5.151ms][ui] GUARD: CaptureModule.init - STOP

12-19 14:30:56.856 13106 13106 V CAM_Profiler: [ 81.684ms][ui] GUARD: CameraActivity.onCreateTasks - [ 5.559ms] Init CurrentModule

12-19 14:30:56.857 13106 13106 I CAM_Profiler: [ 82.735ms][ui] GUARD: CameraActivity.onCreateTasks - STOP

12-19 14:30:56.857 13106 13106 V CAM_QuickActivity: END onCreate: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.861 13106 14259 I FFMPEG : TITLE : Camera Shutter

12-19 14:30:56.864 13106 13106 V CAM_QuickActivity: START onStart: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.871 13106 13106 V CAM_QuickActivity: END onStart: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.872 13106 13106 V CAM_QuickActivity: START onResume: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.872 13106 13106 V CAM_QuickActivity: onResume(): isKeyguardLocked() = false

12-19 14:30:56.872 13106 13106 V CAM_QuickActivity: onResume --> onResumeTasks()

12-19 14:30:56.874 13106 13106 V CAM_Profiler: [ 0.000ms][ui] GUARD: CameraActivity.resume - START

12-19 14:30:56.874 13106 13106 V CAM_CameraActivity: Build info: cm_angler-userdebug 6.0.1 MMB29M 6a26e18747 test-keys

12-19 14:30:56.878 13106 13106 V CAM_Profiler: [ 0.000ms][ui] GUARD: CaptureModule.resume - START

12-19 14:30:56.879 13106 13106 V CAM_Profiler: [ 0.297ms][ui] GUARD: CaptureModule.resume - [ 0.003ms] getRemoteShutterListener.onModuleReady

12-19 14:30:56.880 13106 13158 V CAM_CameraDataAdapter: retrieved photo metadata, number of items: 4

12-19 14:30:56.880 13106 13158 V CAM_CameraDataAdapter: retrieved video metadata, number of items: 0

12-19 14:30:56.880 13106 13158 V CAM_CameraDataAdapter: sorting video/photo metadata

12-19 14:30:56.880 13106 13158 V CAM_CameraDataAdapter: sorted video/photo metadata

12-19 14:30:56.881 13106 13261 D CAM_Storage: External storage state=mounted

12-19 14:30:56.882 13106 13106 V CAM_Profiler: [ 4.196ms][ui] GUARD: CaptureModule.resume - [ 2.026ms] mHeadingSensor.activate()

12-19 14:30:56.883 13106 13106 V CAM_Profiler: [ 4.196ms][ui] GUARD: CaptureModule.resume - STOP

12-19 14:30:56.883 13106 13106 V CAM_Profiler: [ 9.016ms][ui] GUARD: CameraActivity.resume - [ 4.550ms] mCurrentModule.resume

12-19 14:30:56.883 13106 13106 V CAM_Profiler: [ 9.259ms][ui] GUARD: CameraActivity.resume - [ 0.000ms] mPanoramaViewHelper.onResume()

12-19 14:30:56.883 13106 13106 V CAM_LcyLocProvider: starting location updates

12-19 14:30:56.886 13106 13106 D CAM_LcyLocProvider: startReceivingLocationUpdates

12-19 14:30:56.886 13106 13106 V CAM_Profiler: [ 12.045ms][ui] GUARD: CameraActivity.resume - STOP

12-19 14:30:56.886 13106 13106 V CAM_QuickActivity: END onResume: Activity = com.android.camera.CameraActivity@58ef642

12-19 14:30:56.895 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(0.0, 0.0, 0.0, 0.0))

12-19 14:30:56.897 13106 13106 V CAM_FilmstripView: suggesting item bounds: 0x0

12-19 14:30:56.898 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=false

12-19 14:30:56.898 13106 13106 W CAM_FilmstripItem: Suggested size was set to a zero area value!

12-19 14:30:56.898 13106 13106 V CAM_FilmstripView: suggesting item bounds: 0x0

12-19 14:30:56.898 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=false

12-19 14:30:56.898 13106 13106 W CAM_FilmstripItem: Suggested size was set to a zero area value!

12-19 14:30:56.899 13106 13106 V CAM_FilmstripView: suggesting item bounds: 0x0

12-19 14:30:56.899 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=false

12-19 14:30:56.899 13106 13106 W CAM_FilmstripItem: Suggested size was set to a zero area value!

12-19 14:30:56.899 13106 13106 D CAM_FilmstripView: reload() - Ensure all items are loaded at max size.

12-19 14:30:56.899 13106 13106 I CAM_FilmstripView: [ViewItem:0] mData.renderThumbnail()

12-19 14:30:56.900 13106 13106 I CAM_FilmstripView: [ViewItem:1] mData.renderThumbnail()

12-19 14:30:56.900 13106 13106 I CAM_FilmstripView: [ViewItem:2] mData.renderThumbnail()

12-19 14:30:56.900 13106 13106 V CAM_CameraActivity: ignoring storage callback after activity pause

12-19 14:30:56.900 13106 13394 V CAM_CameraDataAdapter: updating media metadata with photos newer than id: 2167

12-19 14:30:56.926 13106 13175 D CAM_MemoryQuery: timestamp=104148811, availMem=664, totalMem=2702, totalPSS=104, lastTrimLevel=0, largeMemoryClass=512, nativePSS=12, dalvikPSS=56, otherPSS=35,threshold=216, lowMemory=false

12-19 14:30:56.937 13106 13106 V CAM_TexViewHelper: onLayoutChange

12-19 14:30:56.938 13106 13106 V CAM_TexViewHelper: updateTransform

12-19 14:30:56.938 13106 13106 V CAM_TexViewHelper: setAspectRatio: 0.0

12-19 14:30:56.938 13106 13106 D CAM_CaptureModule: updatePreviewTransform: 1440 x 2392

12-19 14:30:56.939 13106 13106 V CAM_TexViewHelper: setAspectRatio: NaN

12-19 14:30:56.939 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: 0.0

12-19 14:30:56.941 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.942 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.943 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.943 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.943 13106 13106 D CAM_FilmstripView: reload() - Ensure all items are loaded at max size.

12-19 14:30:56.943 13106 13106 I CAM_FilmstripView: [ViewItem:0] mData.renderThumbnail()

12-19 14:30:56.944 13106 13106 I CAM_FilmstripView: [ViewItem:1] mData.renderThumbnail()

12-19 14:30:56.944 13106 13106 I CAM_FilmstripView: [ViewItem:2] mData.renderThumbnail()

12-19 14:30:56.944 13106 13106 W View : requestLayout() improperly called by com.android.camera.widget.FilmstripView{ba82212 V.ED..... ......ID 0,0-1440,2392 #7f0e0023 app:id/filmstrip_view} during layout: running second layout pass

12-19 14:30:56.945 13106 13106 V CAM_TexViewHelper: onLayoutChange

12-19 14:30:56.946 13106 13106 V CAM_TexViewHelper: updateTransform

12-19 14:30:56.946 13106 13106 V CAM_TexViewHelper: setAspectRatio: 0.0

12-19 14:30:56.946 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: NaN

12-19 14:30:56.946 13106 13106 D CAM_CaptureModule: updatePreviewTransform: 1440 x 2224

12-19 14:30:56.946 13106 13106 V CAM_TexViewHelper: setAspectRatio: NaN

12-19 14:30:56.946 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: 0.0

12-19 14:30:56.948 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.948 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.948 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.948 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2224

12-19 14:30:56.948 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.949 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2224

12-19 14:30:56.949 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.949 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2224

12-19 14:30:56.949 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.949 13106 13106 D CAM_FilmstripView: reload() - Ensure all items are loaded at max size.

12-19 14:30:56.950 13106 13106 I CAM_FilmstripView: [ViewItem:0] mData.renderThumbnail()

12-19 14:30:56.950 13106 13106 I CAM_FilmstripView: [ViewItem:1] mData.renderThumbnail()

12-19 14:30:56.950 13106 13106 I CAM_FilmstripView: [ViewItem:2] mData.renderThumbnail()

12-19 14:30:56.956 13106 13106 V CAM_TexViewHelper: onLayoutChange

12-19 14:30:56.956 13106 13106 V CAM_TexViewHelper: updateTransform

12-19 14:30:56.956 13106 13106 V CAM_TexViewHelper: setAspectRatio: 0.0

12-19 14:30:56.956 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: NaN

12-19 14:30:56.956 13106 13106 D CAM_CaptureModule: updatePreviewTransform: 1440 x 2392

12-19 14:30:56.957 13106 13106 V CAM_TexViewHelper: setAspectRatio: NaN

12-19 14:30:56.957 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: 0.0

12-19 14:30:56.959 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.959 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.959 13106 13106 V CAM_FilmstripView: recycleView

12-19 14:30:56.959 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.959 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.960 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.960 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.960 13106 13106 V CAM_FilmstripView: suggesting item bounds: 1440x2392

12-19 14:30:56.960 13106 13106 V CAM_FilmstripView: getRecycledView, recycled=true

12-19 14:30:56.960 13106 13106 D CAM_FilmstripView: reload() - Ensure all items are loaded at max size.

12-19 14:30:56.961 13106 13106 I CAM_FilmstripView: [ViewItem:0] mData.renderThumbnail()

12-19 14:30:56.961 13106 13106 I CAM_FilmstripView: [ViewItem:1] mData.renderThumbnail()

12-19 14:30:56.961 13106 13106 I CAM_FilmstripView: [ViewItem:2] mData.renderThumbnail()

12-19 14:30:56.961 13106 13106 W View : requestLayout() improperly called by com.android.camera.widget.FilmstripView{ba82212 V.ED..... ......ID 0,0-1440,2392 #7f0e0023 app:id/filmstrip_view} during layout: running second layout pass

12-19 14:30:56.963 13106 13106 V CAM_TexViewHelper: updateTransform

12-19 14:30:56.963 13106 13106 V CAM_CameraAppUI: SurfaceTexture is available

12-19 14:30:56.963 13106 13106 D CAM_CaptureModule: onSurfaceTextureAvailable

12-19 14:30:56.963 13106 13106 D CAM_CaptureModule: updatePreviewTransform: 1440 x 2392

12-19 14:30:56.964 13106 13106 V CAM_TexViewHelper: setAspectRatio: NaN

12-19 14:30:56.964 13106 13106 V CAM_TexViewHelper: aspect ratio changed from: NaN

12-19 14:30:56.965 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.966 13106 13427 V CAM_Profiler: [ 0.000ms] GUARD: CaptureModule.closeCamera() - START

12-19 14:30:56.966 13106 13427 V CAM_Profiler: [ 0.781ms] GUARD: CaptureModule.closeCamera() - [ 0.781ms] mCameraOpenCloseLock.acquire()

12-19 14:30:56.966 13106 13427 V CAM_Profiler: [ 1.022ms] GUARD: CaptureModule.closeCamera() - STOP

12-19 14:30:56.966 13106 13427 V CAM_Profiler: [ 0.000ms] GUARD: CaptureModule.openCameraAndStartPreview() - START

12-19 14:30:56.966 13106 13427 V CAM_Profiler: [ 0.133ms] GUARD: CaptureModule.openCameraAndStartPreview() - [ 0.133ms] Acquired mCameraOpenCloseLock

12-19 14:30:56.967 13106 13427 D CAM_Camera2OneCamMgr: Getting First BACK Camera

12-19 14:30:56.970 13106 13427 I CAM_OneCamera1Opnr: Opening Camera: CameraId{Api2='0',Api1:0}

12-19 14:30:56.970 13106 13427 V CAM_ActvCamDevTrckr: Tracking active camera: CameraId{Api2='0',Api1:0}

12-19 14:30:56.973 513 3488 I CameraService: CameraService::connect call (PID 13106 "com.android.camera2", camera ID 0) for HAL version default and Camera API version 2

12-19 14:30:56.974 513 3488 I Camera2ClientBase: Camera 0: Opened. Client: com.android.camera2 (PID 13106, UID 10038)

12-19 14:30:56.974 513 3488 I CameraDeviceClient: CameraDeviceClient 0: Opened

12-19 14:30:56.977 513 3488 I CameraService: onTorchStatusChangedLocked: Torch status changed for cameraId=0, newStatus=0

12-19 14:30:56.981 927 946 I ActivityManager: Displayed com.android.camera2/com.android.camera.CameraLauncher: +218ms

12-19 14:30:56.982 13106 13106 V CAM_CameraDataAdapter: new photos query return num items: 0

12-19 14:30:56.982 13106 13106 W View : requestLayout() improperly called by com.android.camera.widget.ModeOptionsOverlay{65c3579 V.E...... ........ 0,0-1440,1972 #7f0e0053 app:id/mode_options_overlay} during second layout pass: posting in next frame

12-19 14:30:56.982 13106 13106 W View : requestLayout() improperly called by com.android.camera.ui.BottomBar{223d2be V.E...... .......D 0,1972-1440,2392 #7f0e0065 app:id/bottom_bar} during second layout pass: posting in next frame

12-19 14:30:56.982 13106 13106 W View : requestLayout() improperly called by com.android.camera.widget.FilmstripView{ba82212 V.ED..... ......ID 0,0-1440,2392 #7f0e0023 app:id/filmstrip_view} during second layout pass: posting in next frame

12-19 14:30:56.985 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.985 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.985 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.985 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.986 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.986 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.986 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.986 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.986 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.986 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.986 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.986 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:56.986 13106 13106 V CAM_FocusController: configurePreviewDimensions(RectF(NaN, NaN, NaN, NaN))

12-19 14:30:56.986 13106 13106 I CAM_FocusRingView: Computing center via view bounds.

12-19 14:30:57.186 13106 13106 V CAM_TexViewHelper: onLayoutChange

12-19 14:30:57.188 13106 13106 D CAM_CaptureModule: updatePreviewTransform: 1440 x 2392

12-19 14:30:57.476 13106 13106 D CAM_LcyLocProvider: Got first location.

12-19 14:31:01.978 513 3488 E mm-camera-intf: mm_camera_open:Failed with Connection timed out error, retrying after 20 milli-seconds