How to open Atgames Sega anniversary case?

[TwoTailsSonic]

Hi

I am a noob to opening electrical items but it's never too late.

I have an atgames sega anniversary handheld and notice there was a lot of dirt under the screen(probably dust which has gone in and accumulated over time).
I also noticed the screen is too bright it hurts my eyes. I have other ones and notice the screen is ok so must be that some are set a bit higher or lower. Basically I need to clean under the screen and change the brightness if possible.

I removed the back screws and although the case lifted a bit I couldnt open it. I wrestled with it a bit but was worred its gonna break so just left it. Can you tell me how to open it or point me to a video which shows how to open these sort of devices without breaking the joints or whatever is holding them together.

Also is there something inside to change the brightness setting? How do I go about that?

Please tell me or provide me some resources to open the casing and possibly change the brightness. Thanks