Bought it from japan yahoo auction but doesn't fit for my E61, later I found the note that nonexchangeable retrospectively for my e61.
Should check your car's part number, even same japan imported E61s have various diversity modules.
No corrosion found on the board. I can't guarantee it's working or not in terms of remote key function, radio reception was so well though but auction seller said it's working condition.
based in Wellington and price is $125. Cheers.