I have a 525 efi that shut down at 3800 rpm's with 2 beeps. I plugged in my Rhinda and ran through tests. When it got to the ecu it stopped and said ECU, error cannot complete test. I ran a couple of times to make sure and hoping for a different result.
It has a Whipple modified ECU, so time for a new one or can they fix it?

there is a reason it failed and its on your engine side. That end has to be fixed as well. Yes the PCM can be fixed but depending possible what else failed internally of the PCM. It can be tested and go from there to see how and what internally damage has taken place.. Most important is the engine side will need to be gone over very indepth so it does not happen again. Offering the info and many years of experience to help boaters stay on the water not to have these common issues hopefully again.

Your best bet is to call Whipple,

Funny you suggested Whipple. I called them today and explained that i had a Whipple modified ecu and they put me to a tech. He told me it could be a multitude of thing and was less than enthusiastic about my explanation. I just wanted to know if i should overnight it to have it tested, pay to have a new one shipped or was there different test to check if a failed part would cause the Rhinda reading. Time is limited in North Idaho for our boating season so i was looking at my options to get back on the water quickly.
Ren