The red standby light is on but it wont turn all the way on and show the green light

If your talking PS2 slim there is a yellow thing on the back where you plug in the ac or cable(trying to remember)Put a pencil between the two wires ,Taping helps to .You just are trying to NOT have the cables move.Need help [email protected]

Odd problem you have there

how old is your PS2? the power button might be starting to go if its anything older then 3-5 yrs, when did you buy it and how often do you use it?

also

are you holding the button when you press it? if yes then thats the problem, it only needs a single press, otherwise it just turns itself off again after 1 second of holding it

tell us how you go