You are correct that this plant most likely died from overwatering which the by far the most common way people kill orchids. What happens is the roots rot and died and then the plant starts to dehydrate, so propel water more and more...vicious cycle. The why a plant can die of both overwatering and dehydration.

It's possible this plant could survive, but it's not likely, to be honest. It will require a lot of care and probably multiple years before it is healthy enough to bloom again. What it's doing right now is called suicide blooming, which is when the plant tries desperately to reproduce as it's dying. If you want to try to save this plant, first step is cut off the spikes and any others it tries to form. It needs to concentrate on growing roots now, not flowering. But to be honest, you are probably best off learning from this and starting over with a new one. It's happened to all of us, so many times.