So this afternoon I put half a tank of unleaded in my T6 340.

I then filled it up with diesel before googling and finding out I shouldn't start it or try to drive it.

It's currently been pushed away from the bowsers and left while I wait for a towing company to open after Christmas.

What's the best case scenario, just a drain, flush and refill and maybe some filters? Worst case do I really want to know?