I recommend that you clean the console by taking it apart first, since it's a PS2 Slim, which is “easy” to take apart. The downside of PS2 Slims is that they are prone to malfunctioning, especially when they have been used a lot.

I have the same model of PS2 as you, and I had a lot of problems with the power cable and the disc reader. Good memories that I don't want to relive, haha. I hope you can solve the problem. Good post!