How to disassemble speaker? (sounds really bad at low frecuencies)

Hello!

Until Monday night, the speakers sounded really good, even when playing bass boosted music.

Today, speakers sound very distorted in low frequencies.

What's surprising is that both of the speaker sound really bad.

I believe that the overusage of the bass might have screwed something up.

I tried turning off/on, playing from a different source, plugging in a different outlet, changing plugs of left/right speaker, but nothing.

First test I did was put a song that contained low frequencies. Cone doesn't vibrate as it used to.

I decided to give it a shot and try to repair it myself, but speaker is tightly sealed. No visible screws, not hole to put a flat screwdriver in, nothing. I even tried separating the front, which seems to be a separate part from the wooden casing, but it is sealed as well, to the point the screwdriver is breaking the small pieces of wood.

Any help will be rewarded with infinite chocolate chips cookies and nutella.