I have the nowTV stick and I have connected the remote to my TV so it can Be used for volume control and powering TV on/off. Whenever I turn the TV on, the NowTV stick doesn’t connect. I have to unplug the stick from the USB port and plug it back in to be able to use it.
When you next manage to turn it on, if you search through the options (probably something like settings) then you’ll be able to reset the now tv stick or it might need updating. If you do a factory reset, you’ll have to obviously reconnect it to your WiFi etc but that should hopefully cure the problem. Did for mine a few months back anyway!