IPhone 4 is taking a long time to turn on, its been over a year?

I'm trying to turn on my iPhone 4 and it only show the red battery thing but it isn't turning full on yet. It has been over a year since I last charged it. How long do you think it will take and is there any possible way to speed it up? Maybe by plugging it into a macbook air?

Try home button and power. Or maybe it's just actually dead ish from battery