Button lights up green but why won't it turn on?

My hubby found a 1st gen Kindle Fire in great condition. The charge port seems a little loose but the light on the power button is green. I tap it, it lights up for a couple seconds. I have tried to reset it by holding the power button and the light varies from 2 to 12 seconds lit up. I've held it for 20, 30, 40, 60 seconds. It just isn't turning on. Any simple ideas to fix it? Thanks