The same thing happened with my NAD integrated amp about 7 years ago, I don't remember the model number but it was 150 or 200 watts a channel and luckily it happened when I was in the room listening to music- flames/sparks shooting up through the top plate ! NAD replaced the unit for free and I don't recall if it was even under warranty at the time.
I'd contact them first to see what they'll do; my guess is they'd service or replace it at no charge.
I'd contact them first to see what they'll do; my guess is they'd service or replace it at no charge.