Hi everyone, Dont know where to start

ok here goes...
I purchaced an 29.1 update on ebay, and used it in my mates bmw mk4, worked a treat so when i finally got my mk4 that wasn't the case. i put the car in 1st ignition, waited 2mins for everything to stabalize then i opened the boot and took out the 2004-1 dvd and put the update in. the the screen said, as normal it's in progress and will update my unit. (oh lord

) the screen went blank and stayed like that for 20mins well until i got out the seat went to the boot and saw the power light is no longer active, only the eject symbol was active. so i pressed it and the disc came out, but now nothing, absolutely nothing, other than a black screen with a subtle white background. ive downloaded 29.1 updates from here and the mk4 laughs at me, by making a few little noises like its gonna fire up then stops. Someone please tell me i havn't bricked it and to throw it in the bin.....I'm now back at square 1 on stuck me mk3 back in.... all that for pespective view aye .......
jay