Keyboard.xml button to stop plex process (Plex for Kodi)

Hi all,
So I have recently moved to using Plex for Kodi, was previously using plexkodiconnect but that appears to have become unstable (not finding new shows and alot of them simply won't play), my wife is happy with the Plex for Kodi add-on (so am I).
I now have a button mapped to jump straight to the script (runscript(script:Plex) or something like that), but what I have found is that if I don't exit Plex and instead jump straight to say live TV the controls are still Plex based not Kodi based, meaning that my remote does not work as expected. Therefore (and I asked this on the Kodi forum but can't get it to work) how do I map a button to stop the Plex script from running (i.e. same as pressing back lots and then clicking ok). The guy on the Kodi forum mentioned sendclick and control 500 but I'm not 100% and what I have tried did not work.
Cheers