I don't know about the plug not going in, but I once got a phone call from my friend who has a Bernina, she even went to the trouble to hold the phone near her machine so I could hear the noise it was making. It turned out that her bobbin winder catch was engaged, so it was spinning round without a bobbin on it. Just something to check, in case you have accidentally knocked yours.
If it isn't that, I hope you get it sorted soon, at least it's still under guarantee.