It's been a while, but I am thinking you missed a few of the bolts, as you noticed there are lots of bolts there.
Look underneath the rear area as a start. As a recall there are some allen headed bolts in there that are buried deep. Will take an allen headed socket and a medium to long extention to get to them.
The lower casing will lift right off when all the fasteners are loose. It is not held on with much, maybe a thin film of sealant.