i've bought a 2013 21.5 on eBay. Arrived this morning, but the keyboard has terrible battery acid leak. It will not work at all. switches on, but nothing else. I have another one, from a previous mac, but that wont pair either. My old PC keyboard works, but will not type an @ i'm back on PC now, temporarily. Haven't used a mac for a while, so a bit rusty! In Finder, I cannot see Macintosh hard drive, the only drive listed is an external drive that's plugged in. I want to have a look at it & also transfer some data onto it Any thoughts?