I'm a military pilot and, if I can give my two cents here, among the wise of 9GAG, this is a very strange way to die.
The aircraft did not and could not stall, as it has a very different downing pattern.
This was not an engine failure, as that would have resulted in glide.
This kind of downing is only possible, if you do a nose down and keep it that way. The wings were broken off already, most likely and that's why it went this straight down.
Software failure is very... strange this way, because that would require the software to think you have immediately shifted 90 degrees in your course upwards. The autopilot would simply drop control back to the pilot.
One plausible way is that they had a bank error, did not correct, fell out of course (turned 90 degrees, and then lost lift, nose down and it was already over) and then it was too late.