Decode legacy fire panel trouble and supervisory messages with common code guides, grounding checks, loop isolation

https://pub-4af61f5d1a2a4eab9a58c005d0d1affe.r2.dev/new-haven/data-cabling—south-central-ct-2026-mammoth-security.html

Decode legacy fire panel trouble and supervisory messages with common code guides, grounding checks, loop isolation, and testing steps that restore reliability without premature replacements.