Nintendo 3DsXL won't charge or turn on

I didn't even know these had batteries. I am trying to help my 12 yr. old special needs nephew fix his 3DS xl. It won't turn on at all. It took a charge, at leaset I think it did. I pluuged it in & light was orange, then turned off when it was done. Still nothing happens. So I took screws off back, & found battery, like you suggested to someone else. I notice battry says rechargeable. How do I recharge it? I didn't even know these had batteries. I am trying to help my 12 yr. old special needs nephew fix his 3DS xl. It won't turn on at all. It took a charge, at leaset I think it did. I pluuged it in & light was orange, then turned off when it was done. Still nothing happens. So I took screws off back, & found battery, like you suggested to someone else. I notice battry says rechargeable. How do I recharge it?