Trouble with the cooling fans

Back in May I had the coils packs replaced under warranty by the local dealer.

Last week I was caught in traffic after a bit of a run. After a few minutes the temperature gauge started rising until the dash told me that I should stop and let the car cool.

The cooling fans did not kick in.

Turning up the interior heater to maximum sorted out the problem.

On inspection it appears that the air intake top cover had not been refitted properly, had got wedged in the larger of the two cooling fans.

Removing it did not resolve the problem.

Upon checking the fuse box, it was clear that the 50amp strip fuse had blown, meaning that no current would flow to the fans.

Today I changed the strip fuse; now the main cooling fan will not stop spinning, even with the ignition off, key out, and the engine cold.

Any ideas??

I know that water ingress often causes fan issue, but this clearly is not the issue here.