Pray?
Seriously, these are so complex that you can't fiddle with a multi-meter and a screwdriver and hope to figure anything out. You need to get her "plugged in" to see what's up.
If your battery is fully charged and you have her hooked to a tank full of gas that's about the extent of troubleshooting the average guy can do in his driveway.
I work on Mercs but don't have a DDT, so aside from changing an impeller, filter and plugs, Opti's (and most 4 strokes) get directed to the authorized Merc dealer across the street from me...