F225 electrical power problem

[gradyfish265]

I have 2002 Yamaha F225's with just under 500 hours on them. Engines were tunned by Yamaha about 80 hours ago. Ran 15 trips this season then had an issue with my stbd engine...we were running and the engine dropped to 0 rpm from 4200, then then jumped back up. It did this 2 times over the course of 2 trips. On the third trip it did it again and never came back up. We now have no power at the helm for this engine. When we turn the key at the helm, the guages do not go on and the starting sequence does not occur...ie no beeping. Fuel pump does prime though with key in middle position before starting. There is no power to the trim/tilt on this engine as well since this has occured. The other engine works fine with no issues pertaining to this. I have removed all battery connections leading to the engine, batteries, and battery switch and cleaned all and rewired them, engine is getting power from the main wires. I had a mechanic work on it and he had luck getting it going again by unplugging and reconnecting the trim tilt pin connector. Ran the boat for about 15min and does not work again. Tried the pin connector again and did not work this time. Anyone have anything similar happen, any input into what might be causing this? Would be nice to narrow down the problem instead of having the mechanic and myself go through thw whole engine trying to find the issue. I've been wondering if it is the ecu...but if I'm correct, my fuel pump shouldn't prime then? I've thought about a bad ignition switch, but then why no trim tilt both from the throttle and engine itself? Could possibly be a bad ground somewhere? Would love to get back out there and not have to deal with this.

Any help would be much appreciated!! Thanks in advance!!!