Hi,
Ive pulled out my BM54 today (while working on HIFI upgrade). You mentioned the 29F400. I found an "29F400BC-70 0448 F84S" on the rear side of the PCB with 44 pins (Atmel isnt mentioned - instead theres a big "F" - FUJI maybe???). I still think thats it - what do you think? There arent too many SMD parts on the rear side so you would have quite some room to work...
Ive attached a picture. Bad quality though (cell phone). Now lets see if I can buy one of these chips
Another idea... before I end up buying a programmer for one time use Ill try to find someone with an adequat programmer
Edit:
Ive done some research. The 29F chips are flash eproms. Ive found an online store that sells these for 7 Euros. They can also program it for you charging 10 Euros for each one. The only problem is that they dont have the exact same chip in stock. So Ill have to contact them to check if they have any 29F thats fully compatible.
Cheers