I unplugged the TV 2 min from the wall then it worked !

Was just going to suggest that. TVs, particularly Samsung seemed to lose track of the ARC connection and need to cold reboot to reset.

Had exactly the same problem - thanks for the solution, it worked a treat!  On a side note I often get problems with a Philips Blu Ray DVD player plugged into HDMI 1 conflicting (ie stopping the Beam connecting) and the work around is to put the DVD player on first and the TV once it’s up and running.  Anyone else have a similar problem or know of a more convenient work around??

You could try to use a CEC-killer between DVD player and TV.