That 28 watt power draw would kill any Leaf SLA after +13 hours of use given the SLA was brand new, fully charged when you started. I'm guessing that either you drive the Leaf often enough to not encounter a dead 12V battery or the mystery load must be stopping at some point?
At this point, I have to pull off the negative terminal if I am parking for more than a few hours, otherwise it will be flat at the end of the work day.
I have the factory service manual and have been looking through the wiring diagrams. One relay is the SSOFF (VCM Self Shutoff) relay. Its signal comes from the VCM, and its purpose is to turn off the VCM. Its switched line goes right back to the VCM. From the FSM-"VCM also activates the SSOFF relay so that it can shutoff VCM power when VCM stops (self shutoff)."
The second one is the M/C relay, which recieves its signal from the VCM, and is responsible for supplying power to each ECU in the VC system. So it seems that something is keeping the system from turning off. I don't know if that is a faulty sensor or switch that may have gotten damaged fromt the rain, of if that was just a coincidence.
I guess the next thing i can do is bench test the two relays, but after that I am not sure where to go.