I’ll preface this post by saying that my alarm-monitoring company is coming out next week to service and fix my issues. But I’m racking my brain over what went wrong, and would just like to discuss the situation to see if any of you have any ideas.

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I have a Honeywell Vista-15P alarm panel that I had professionally installed in 2017. It has one keypad, one remote key fob, and one cellular communication module. I have no local phone service, so a cellular connection was my only monitoring option. The unit has been rock solid since install. The only change has been a swap of the cellular module by my alarm company during the 3G sunset.

I recently decided to buy and install an Envisalink 4 for the purposes of automating arming events. If you’re not familiar with Envisalink, it essentially acts like a secondary keypad and can do everything the OEM keypad can do. It’s just the circuit board with an RJ45 (“ethernet”) port and the four terminal ports (BRGY).

Now I’m a bit of a DIY’er, especially with electrical and electronics. I was not, and am still not intimidated by the circuitry of an alarm panel. So two days ago, I unplugged the panel’s AC power source, disconnected the battery terminals, confirmed the unit was de-energized, and installed the Envisalink. Once I powered everything back up, things were looking great. The Envisalink worked better than I expected, and its API seamlessly integrated with my home automation.

But last night, I noticed the red FAULT light on the cellular module was slowly blinking, indicating a failure to communicate with the panel. That FAULT condition would cycle on and off in about five minute increments. I could not recall if that light was blinking prior to the install of the Envisalink. So I did what any IT pro would do and backed out. I powered off the unit again, disconnected Envisalink, and restored power. But the FAULT condition in the cellular module persisted.

I contacted my alarm company, and they confirmed that right after I installed Envisalink, their log shows repeated Supervision Lost events, followed by Supervision Restored events. This continued despite the Envisalink being removed. I double checked that I wired the original equipment correctly and that the terminal screws were all screwed tightly, and even did my best to reduce favorable crosstalk condition between the wires for the cellular module, keypad, and siren.

Today, while the system was not armed, the siren randomly sounded for two seconds and stopped on its own. I ran down to the keypad and found that it was in its boot up sequence. The keypad then went into a rapid beeping sequence, and over the course of the next hour would repeat this and show CHECK BF (communication failure) or CHECK 94 (telco failure).

At this point, we (me, spouse, and alarm company) just decided to disable the panel entirely until it can be serviced next week.

Obviously, I see the sequence of events and the problems are clearly my own fault. But I am struggling to understand what went wrong. Everything is wired correctly. The Envisalink worked great when it was installed, but the post-install problems persists even though it is disconnected.

I only have two theories:

• The Envisalink did, in fact, cause an electrical issue that damaged at least the cellular module, or at most the whole panel. EyezOn (Envisalink vendor) obviously denies that anything is wrong with the unit since it was working as expected.

• De-energizing and re-energizing the panel for the first time since it was installed six years ago damaged the unit.

If anyone has any guesses or follow up questions, I’ll gladly entertain them. I won’t really know the full extent of the problems until next week.