External door will not unlock

Put some pressure on the key and thump the door with the flat of your hand close to the locking point. May help to release it.

Failing that, if the hinges are accessable you will have to remove the door. If not, I think it will have to be a careful jemmy job. Prise the bottom of the door out and get an assistant to prise the top of the door down. Helps if the panels are removed from the door first as they make it rigid.

Cheap locking mechanisms can be defeated this way, But not all.

In fact, try pushing it in all available directions (one at a time!) - in, out, up, down (the latter two with a jemmy or similar) - whilst trying to turn the key.

Failing that, tip off the police that there are terrorists hiding in the house. They'll get it open!

"Swedor" doesn't help a lot, but the pictures on the Norwegion site look as if they are plastic doors rather than timber.

Try pushing the top of the door harder closed whilst trying to turn the key in the unlock direction. I suspect that top bolt is binding and being held by the pressure from the seals.

How long ago did the mechanism last work?

Before doing anything that might damage the door it might be worth having a real locksmith take a look at it. If there is a cute way of defeating the lock and/or freeing it then they are likely to know it.

It is possible the thing is slightly out of true and so friction on the upper lock surfaces is preventing it from moving. A well placed shock and/or a trace of penetrating oil might just free it up.

Wot no angle grinder? :)