Unable to install Plex on my RN102

Good afternoon can anyone help please.

I have a ReadyNas RN102 running Plex to view videos on Fire TV, it has been running with no problems for over 12months, last weekend the Fire TV came up with an error saying iy couldn’t connect to the server.  While looking at the downloaded PLEX app on the Nas I inadvertently uninstalled PLEX and have been unable to reinstall.

I notice that PLEX is no longer in the available apps list and so I followed the below process looking at advice from the community

From PLEX TV I downloaded ARM 6.x to my laptop

Then uploaded to my NAS, upload goes to 100%, and moves to a screen that says Installing application, this process may take a few minutes please wait, the processing icon revolves but never finishes. I’ve left this running overnight without success.

When the is processing is underway  I cannot access any of the other admin functions, not sure this is normal.  In between trying to upload PLEX I tried loading one of the available apps and that loaded without an issue.

I’m now struggling for ideas, can any one assist please.

Pete