How to disassemble the Asus RT-AC55UHP router?

So i have this router for a few moths, but after a prolonged use like going on GTA online or other network intensive applications for a few hours. The connection started get unstable like dropping wifi connections. Sure something went wrong inside the router . I try to tear it down and apply a few heatsinks. After unscrewing the four screws under the bottom I use a card to loosen the clips, yes this works for the front clips, but the clips that are at the back of the router, the left and right side still get stuck. I checked out for lot of tutorials that for similar models. None of them work. So anyone can tell me how to loosen these clips in a nice and safe way? I tried to figuring it for hours!

P.s.: the router's warrenty has already expried.