Power is black but I can hear all sounds at back.

This is the second time I've been in this situation. Last time my brother had sat over my tab and it was like the black shades coming over and it was working fine but after 10 to 15 min when I used it back again the power was black all I could hear was sounds of power key. That time we had gone for professionals and we got it repaired. This time I don't want to go again to electronic shops. I tried all those solutions (pressing power key and volume buttons together) and as far the other one; removing the battery and placing the battery again..as many say my tab is SG Note and in this one it's really hard and confusing to know how do you open the back cover so I couldn't do try that solution. Anymore solutions or ideas please. I'll really appreciate. Thank you!