pity but it was their fault for ignoring safety rules. their hydraulics is faulty and its hydraulics that lifts that whatchamacallit thing that lifts. they should either work under chassis or if they have to really work in between sections, they should have propped the sections with something solid. one mistake and everything you worked for is wasted. including you.
The prop, as you say, undoubtedly failed. Hydraulics can not be worked on while under load.