Mid 2012 MacBook Pro won't power up

I have a MacBook Pro (mid 2012) and when I press the power button it won't power up. The MagSafe power adapter doesn't light up when plugged into the laptop. Do you think the issue is a defective battery or something else? I would swap out the batter but I don't have a spare. Would appreciate comments from someone who has experienced this issue or some ideas?