A very thin lever, such as a
modelling scalpel, is usually helpful to work around the crack, locating the
clips, and springing them by twisting.
I use a thin propeller blade (nylon is the best) from the hobby shop
for this. I have it cut in different pieces to slip under the seam and
pop the snap togethers.
I would also carefully check the battery connectors esp. where it
connects to the board. Also some of the Panasonic battery connectors
can get flattened in the battery box. These can be pried out to restore
the connection. These often look like a spiral.
Richard