Why won't my camera turn on?

No matter what I do my camera just won't turn on. I've charged the battery fully and tried it out. That didn't work. So, thinking that this might be an issue with the battery I bought a new one, charged it fully, and tried it out. That didn't work either. I looked online at guides, and it said try pressing the playback button. It still didn't work. What else can i do to get it to turn on?