Hi! A curious electrical issue that puzzles me:

Our 21 DC has a 2013 year VP V8 270-B, first installed in early 2015. Everything has been smooth cruising, until last week when at 10 knots the engine just stopped and hasn't started since.
It seems to be an electrical issue inside the engine: the engine cranks ok, all relays & fuses are ok and get power but the spark plugs won't fire. All outside connections seem to be fine, too

The boat is now sitting at a certified VP service waiting to get checked.

Meanwhile, any guesses of what might cause this?

I would think about ignition coil. it might be included in your spark plugs parts and be defect.

Thanks. Googled around a bit, that could be it.
Any othet opinions?

Did you check your killswitch?