When they lost contact, the lander had a 50m/s lateral velocity. It probably slowed a little more after that, because the lander was solely under the control of an onboard computer that was running a pre-programmed landing cycle, but it probably didn’t slow by all that much. My WAG is that they miscalculated the terrain in the vicinity of their landing site, and the thing plowed into a hillside that was taller than they thought, and was probably buried under regolith.
You’re probably right. A velocity and/or terrain problem. Aren’t there areas of talcum powder like fines? Pieces could be buried in some of that, or even coated in some of that kicked up by the impact. So not as reflective (natural camo) as expected.
re: “When they lost contact ..”
I was ‘there’, watching the live webcast. Know all about it.