Well, I found the problem on why that particular module failed.
Long story short the homeowner hired a local "handyman" for some work around his residence - and the handyman re-wired the field connections, according to the homeowner.
When I up-dated and expanded the system I noticed a bunch of 16 & 18 gauge wires looped and taped together leading into the garage.
As I removed the wires, section 5 was apparently shorting out inside the wall - seems the handyman added wire to this section to reach the controller and the joint was not protected - bare wires just twisted together. Furthermore he had changed colors so the red 16 awg was extended with a white 18 awg then back to a red 16 awg.
Basically looked like someone crapped a bunch of wires in the wall.
Nice Try = You Suck Spelled Differently