Unplugged Volvo Penta Electronic Throttle

I just bought a 1998 21' Cape Horn Fishing boat with tower. It has a Evenrude E-tec 200 that is driven by a Volvo Penta electronic throttle control. When I turned off all the batteries, I noticed the lights were still blinking (solid green/blinking red) on the throttle control panel. I felt this would eventually drain the batteries so I tried to disconnect what I thought was the fuse (not!). I unplugged one of the lines; then the system went dead. I plugged it back up but it did not work.

Any assistance anyone can provide would be greatly appreciated as my wife is going to kill me if I spend another penny on this boat.