Does anyone know how?

Its a Ford Sound 2000, model 2005. As fitted to XR3is, XR2s and the like.
(Top spec in the 80s )

I've tried entering the wrong code three times and now instead of presenting me with three flashing dashes it shows three solid dashes.
According to the manual I should be able to leave it off for 30 mins and try again - this doesnt work.

Please help! I've got nothing to drown out the misses constant chattering now and I cant be arsed paying some pikey scrap dealer a fiver for a new one.