it happened again to me.
i found that you don't have to do all that complicated stuff.
Just hold down the on/off button in the top left of the remote for about 20 seconds.
Found that if I went into the apps store with all my apps .update the Amazon prime app then it actually came on for the first time . I'd get the whites dots for ages then it would just go off .
I tried signing in and out of my Amazon Account. That didn't work. I uninstalled the app and reinstalled it. that didn't work. I unplugged my TV for one minute, then plugged it back in and pressed the power button on the Samsung remote and held it for 30 seconds and that did work for me.