Chromecast with google tv wont factory reset

[dunkiegaming]

My chromecast just won't factory reset, not via the settings app and not via recovery.

If i do it via the settings app, it restarts, shows the google logo with erasing and then shows the android robot with text "Fault" and reboots like nothing happend.

If i do via recovery, it says

E:DM_DEV_CREATE failed for [system_a]: Device or resourse busy

E:Could not create logical partition system_a as device system_a

E: Unable to map partitions to complete merge.

Unable to check merge status and/or complete update merge.

Unable to check update status or complete merge, cannot wipe partitions.

What should i do?

[Ashepherdson]

Did you try physically pressing the reset button and holding it for the factory reset (really the ONLY way I recommend you do it frankly) 

[dunkiegaming]

Yes i tried that method too but it also shows the android robot with text "Fault".

[Ashepherdson]

How old is the device? If still under warranty, I would suggest trying to get it exchanged.