It's Scando, so i would imagine that if the relevant ministers in FI SE NO all sign off, and no major market players (like Fortum) object, then they'll unwind it and fall back to replaying the previous day's bids. Or is this impossible ?
Let one who makes mistakes to pay for them.
However this does not prevent doing other trades on the top this trade to other direction. It is the question who catches the falling dagger and pays for the mistake of others.
See a similar story here
This is pretty clearly NordPool's fuckup. There's no way in hell this bid should have gone thru without human review. Seems clear that their UI is to some degree - in some critical spot - fragile, user-hostile, ill-designed.
You can say that in analogous cases, finance firms have been put out of business by bad bids caused by slipped fingers. Granted. But in this case you're throwing a wrench into a power grid, with the potential to cause a system disruption, in winter no less.