Engine locked up

I had the main crank seal replaced on the car and I drove it home from the shop and parked in my garage for about two weeks. The next time I drove the car I got approximately two miles from my home and the car started making this loud grinding sound and then the car locked up and all the warning lights came on inside the car and it completely shut down. My question is, could this have been caused by the crank seal being replaced incorrectly or the fact that they did not add oil or do an oil change after they replaced the crank seal. The shop that did the work said that the engine needs to be replaced. I never had any problems with the engine on that car.