Judging by the timeline on https://www.myshiptracking.com it looks like something that would be called pilot induced oscillation in aviation. Obviously speculation on my part, could be that loss of power weakened control authority over the ship and it became hard to manoeuvre.

The ship comes around the curve travelling north close to the outside (right, east, starboard) shore then overcorrect to the west shore then overcorrect more gravely to the east again and run aground.