trying to remove electronic readout

I'm trying to remove the electronic readout to see if it is wet inside, etc. It has three small bolts holding it from underneath. Two of the bolts turn but don't come out - feels like nuts spinning inside. Does the top snap off ??? It feels like the tabs on the side might push it to release the top, but I'm afraid to get too aggressive and break it. Can anybody advise that's been there before ?

Only been there for battery change. Did not see any break point!