On 05/06/2020 at 01:45 am, the crew started assembling 13-5/8” 10K BOP stack using the rig crane to prepare the assembly for offline pressure testing. After bolting together the crew removed the lifting slings and shackles from pad eyes to release the crane for the next task. Once removed from the lifting points, the crane operators started raising the block and chain slings. As he continued to raise the block, the slings caught on the upper ram bonnet locking screw which caused the BOP assembly to topple falling on the crane cabin which got crushed and damaged.