??? So you are thinking that you can get into home screen if the power button is fixed and fully working?
I smell a factory reset in there if you can't really recall the password, regardless to your power button.
The power button is irrelevant in this matter. I 'assume' you're referring to the 'lock screen' passcode. If so, you're going to have to connect your iPod to your computer and then restore it via the computer's iTunes app.
If you're trying to bypass the iCloud activation lock, your only alternative is to use Apple lost password feature via the iCloud website.