re: That is what happened to Mars Climate Observer
Totally different failures for MCO (Mars Climate Orbiter, not observer) and Beagle 2.
MCO was crashed into Mars by its engineers due, in part, to the now infamous newtons/pounds issue. As a spacecraft design, it was sound. It was copied, nearly built to print, to make Mars Odyssey 2 years later.
Beagle 2 didn't have enough time, money, volume, mass, testing. It's instrument package was superb - but also under-tested. There are elements of Beagle 2 that would make a great payload for future missions, and hopefully that is what Exomars will become.
Doug