I do not believe that the calculations were flawed. I believe that the martians shot it out of their air space. We will have to give a probe another try. We also need to take a manned flight to mars and back. This way we can manually place probes at various points, We can make sure the probes make it safely to the surface or know why there did not make it. Thus giving us more information about this planet.
Novel analysis technique helps solve Beagle 2 mystery
The Mars lander Beagle 2 deployed at least three or all four of its solar panels, scientists report. The probe was discovered on the Red Planet in November 2014, but uncertainty surrounded what had caused its failure to communicate with Earth. Now researchers say that Beagle 2 did not crash, but landed and probably deployed most of its panels. Ref. Source 2w.