PS3 wont turn on, no beep

My PS3 is kinda old so i figured this would happen eventually. When plugged in, the light is red (as usual) and when i press the button, theres no beep. The light is green for maybe 30 seconds, then the light turns off entirely. If i press the button again after that, the light turns red, and the same thing happens again. I tried pressing and holding the button (while its red, it turns to green when i press and hold), but after a while it turns back to red. I've tried opening it up (we assume its maybe too dusty?) But we dont have the correct screwdriver to open it, so were waiting to buy a new one. How can I fix this?