Is this part of the testing of new heat shield options?
No, it appears that one of the engines had an explosion which knocked out 3 others and caused it to loose directional control. It started tumbling out of control and they could not get the other engines to restart. There is a video where they show the engine bay and one engine has a long bright red crack before the problems started. Had it made it 20 seconds longer the engines were scheduled to shut down and it probably would have been successful.