External front side is a a plastic screen glued to the equipment. To disassembly it, insert a knife to cut the glue. It is soft glue, silicone, probably.
Be carefull to not damage external plastic with knife
After screws removed, it is posible disassembly equipment by inserting a flat screw in the sides. It is strong enough to resist some efforts. Be carefull anyway.
I see that your weather box LCD screen in your pictures is not working. I have just fixed the same issue on my BAR800 weather box; if you have not fixed that issue yet, I can tell you how to do that.
To solve the missing digits and segments on the LCD, in my case I just inserted a small bent paper on the flat white cable (strip) to add a small bit of more pressure into the connectors.
You can read more on Stackexchange searching for partially-broken-lcd-missing-segments