Does anyone know what to do about an Enphase Envoy error message "Envoy Failure", and the event (from the events log), "Flash memory filled over the threshold limit, 94%".

We have a system of Enphase M215 micro-inverters and the Envoy monitor.  Our system has been running since November 2012.  I connect the Envoy to my network at least a few times a week in the evenings, except during a 3 month period between Oct 2015 to Dec 2015, just to check (locally, not in Enlighten) the system daily production.   The reason for not connecting the Envoy to the network (and thus to the internet) 24/7 is because I'm worried our solar system (and network) being hacked into. 

Then last week when I made my daily check on the Envoy monitor screen I saw the aforementioned error message.  I rebooted the Envoy by recycling the power to it and thereafter it would operate normally for a few hours.  I called Enphase support and the rep suggested he would run some background scripts to clear some files in Envoy. Also, that I leave it connected to the network for a few days in hopes that the Envoy uploads data to Enlighten and thus clear some memory space.  The rep thought that by not having the Envoy connected to the network all the time was a cause to the memory filling up.  But that would mean that homes without an internet connection or owners that decide not to share their pv data would have memory space problems.  I thought that connecting the Envoy to the internet was an option, not a requirement unless software updates or grid profiles changes were needed.  Anyways I worked with the rep, but the Envoy could only run for a few hours before it fails and need to be rebooted so not much uploading to Enlighten happened.  

Then it got worst, where recycling power to it would not help to boot it up.  In the last call to Enphase support, a different rep said that they now would not be able to remotely log in and troubleshoot the Envoy in its current failure mode. Therefore, he suggested I get a new Envoy (cost $500+) and then have it connected to the network 24/7.  I am hoping to not go this route for a solution.

I have seen a youtube video of the Envoy circuit board which has a removable flash memory card (possibly used for data logging).  Would a possible fix be to clear or replace and reformat that memory card.  I would also need to figure out how to disassemble the Envoy without breaking it.

I have been assured by Enphase support and also have verified that the PV panels and microinverters can function normally without the Envoy.  But as a system owner the monitoring system is needed.  Thanks for any helpful suggestions.