"No" doesn't mean anything if you don't follow through. So, if she's not allowed to touch it, don't let her touch it. Stop her hand before she touches it, put a gate up in front of it (or a cloth or anything that takes time before she can get to it), or take her out of the room. Then give her some buttons she CAN push.
Redirect doesn't mean "hey, you want to push buttons or jump on the couch, but we don't like that, so here, sit and read a book or shake this rattle". You aren't meeting her developmentally appropriate desire to push things (like buttons) and experiment with cause an effect - so find things that do meet this desire.
And be 100% consistent. If you let her get away with something you've told her not to do, you've actually just taught her to keep trying. To keep trying so she can figure out how many times or in what special way she has to do it so that she gets away with it. Make her bored of her efforts, so that she learns NOTHING she does will let her do whatever you are telling her no for.