I tried charging my blackberry playbook today. The tablet hasn't been used in some time, it was my aunt's and she gave it to me but i don't really know how to use it. I tried using some tutorials on yt but i can't even turn it on to get started. When i plug it, it flashes from time to time (red led and sometimes yellow led) and even though i left it 2 hours to charge it won't turn on. Any ideas ?