Found: Beagle lander.
Solar panel malfunction
prevents contact home.
In 2003 the Beagle 2 Mars lander arrived at Mars and was expected to make its first communication from the surface on Christmas day. The lander remained silent. None of the 24 attempts to make contact with the lander were successful, and without a sighting of the lander it was difficult to know what had gone wrong.
Now, Bridges et al (2017) have identified the lander using a recalculation of the predicted landing area and Mars Orbiter imagery of the target area. The lander was found within 20 kilometres of the original landing target and the images suggest that not all of the solar panels deployed successfully. Without the panels properly deploying communication would have been impossible. These findings suggest that everything appeared to be going well with entry, descent and landing sequence until a final fault during solar panel deployment.
Original research: https://doi.org/10.1098/rsos.170785