Yea well, I'm a big believer in if it ain't broke don't fix it. I'm also not a fan of subscription software. My home automation computer is not running the latest and greatest (although that's debatable) OS, that's what my laptop is for. It's running Mojave which they dragged me to kicking and screaming because I updated my Mac mini and it isn't backwards compatible. I think I was running Sahara prior to that. I have whatever the next Indigo version was after 7.1 but it wasn't a case of just installing it, it changed somethings which I'd rather not do so I stayed on 7.1. Every time you update OS and sometimes software things get broken.
I think my problem was the battery. Last time I had anything to do with the panel was 4/17 when I changed the battery.. I checked the voltage of the power supply (18vac) and on the battery (both connected and disconnected) which was around 13v. I went ahead and changed it to a UPS battery I had sitting around. It needed to be charged because it had been on the shelf awhile. I got a battery error on the keypad with the new battery so I don't understand why I wasn't getting any sort of error with the old battery. What I was getting was the errors in indigo log file, chirping on the keypad with no error display and periodic Security Event: Fire Trouble emails. I'd get a series of 3 trouble and 3 restores over 3 minutes and then nothing for a few hours and then repeat.
Prior to replacing the battery in 4/17 the only other problems I've had was with the smoke detector which I had replace in 2012. So I got a new smoke detector which did not fix the problem. I was getting the same emails with the new smoke detector. I disabled the DSC plugin to see if that was causing the chirping on the keypad. It wasn't. I had also put the old battery back in thinking that the battery error was working. Finally settled on putting the new battery back , letting it charge overnight. Last trouble email was at 12:06 am today, chirping seems to have stopped so maybe the problem is solved. I have updated the plugin, also logged into EyezOn and saw a firmware update was available (no telling for how may years) so updated it. No new Indigo log error and after sitting overnight the old battery is reading 10.1v so I guess it can't hold a load anymore. Next step will be to put the old smoke detector back in but I'll wait a day to make sure everything else is working.
If you aren't working with things every day and it's only every 4 years or so you tend to forget how things work. It's a credit to the DSC alarm panel, the DSC plugin and Indigo that it just works, you don't have to screw with them all the time.