completely stuck bolts inside luggage box

[itchy]

Hello, I'm trying to remove the box to be able to bleed the rear brake and I've followed Haynes and got to the bit where all you need to do is undo the four internal bolts. 1 came out with immense difficulty but I cannot shift any of the others. I've tried whacking the Allen key with a copper mallet - no go - any ideas? thanks.

[ploddit]

Is this a Deauville?
Spray with penetrating fluid for a few days, if you kill the allen head try a torx bit hammered in.