I imported some god awful late 80s BMW 7 series from Japan many years back. Think it was a 750il. If memory serves me correctly, there was something unusual about the key, whereby if the car battery was flat, the key would neither open the car {frequency} nor could you manually open it. Battery inside the car under rear seat just made it worse. BmW refused to help given it was a grey import. So i priced up replacement cost for all windows, and after finding the windscreen was cheapest, called the glass fella out to my house, threw a brick threw the window, got inside the car... Eventually... And waited for new glass.
And then fixed the **** battery... Which weighed a ton.
Please dont do that with your maser.