Apparently is in mute mode.
Press and hold the up key (or the left don't remember which I haven't been using firesticks for a while) until the volume bar shows up.
Uninstall the app and reinstall. Since the mac is the same, it will be activated so not to worry.
Upload the list again.
This happens sometimes as the TV cannot delete all cache.
You can do it using your mobile. Install "apps to fire", download the apk to your mobile and upload it to firestick.
You can do this to all .apk
Don't forget to enable develop mode on the firestick and allow unsigned apps to be uploaded.
I don't do it in my panel. I do it when provisioning the client. or I just change the line before giving it to the client.
I pretty much use clientportal.link changing it manually before uploading it at sip******* WARNING FRAUD **DON'T BUY** PLEASE REPORT TO ADMIN ******* or handling it to the clients. Mag boxes, I always use that link.
I have dozens and I don't have a single issue with them :D
Furthermore, clients now use only the TV Remote as they are CEC complaint :P - As long as they are genuine
It's a long shot but try to clear all cache - Settings > Applications > Manage All Installed Applications and try to delete as many apps as possible on the bloody thing.
Another issue could be the power source of the Firestick. Have you tried a power supply (I suppose you are using a cable...
The file is split by countries only.
But you can download the file, edit it accordingly and create your own categories and then upload it to SmartIPTV.
It's a simple text file (download the m3u with options file). As soon as you open it you will immediately see how you can reconfigure it.