I don't know if I am missing something, but were there underground power cables.....right through your garden?
Yes, they come up from the road under my front garden to the cellar. The front garden gets all the sun which is why I have my wee allotment there. It is an old Victorian house, too old for there to be any plans so they spent ages trying to find the cable in the dark. The cable that burnt out was probably the age of the house. They managed to take out my neighbours electricity in the process; he wasn't happy!
I would try and put the soil back from the lawn and raised bed area but am not sure if there is a correct method for covering high voltage cables and junctions. Plus there is a large keep out barrier by the front door. I think it is best to wait for the contractor to return.