There could be larger issues going on here. Japanese maples are especially prone to a soil pathogen that can cause extensive dieback and even death. Disturbing the root zone is one of characteristic ways of introducing the problem to the plant.

I'd be a bit more patient and wait for the tree to leaf out more fully (compare against the status of other JM's in your area). If there is really no significant foliage development and a significant portion of the tree is dead, then removal should be considered.

What is your location?

I'm in the DC area. I have another JM in the yard that is doing great. If the tree is going to recover, how long will that take? Would pruning the tree help?

So I noticed there are green lichens on this tree. I'm afraid that this is the same thing that killed the huge oak in my yard. I've posted a pic of the tree trunk. Please tell me there is hope.

If it is going to recover, it will leaf out in time with other JM's in the area or shortly thereafter. If no foliage showing by the end of May, then chances are it is done. Pruning will not help one way or the other at this point in time but could be necessary later if only part of the tree leafs out.

And as to the lichen, it is harmless. It causes no problems for the tree at all but it frequently colonizes trees that are on the decline for some other reason. The lack of vigor and resulting lighter, sparser leaf canopy allows for more rainfall, sunlight and air-borne nutrients to be accessed by the lichen.

One last pic of the foliage. I will keep an eye on everything and hopefully it will recover by the end of May