Answer to: My tab 4 screen doesn't workWas it dropped? If it was dropped, the cable that plugs the display into the board could have come out causing the screen to go dark. If not dropped, it might be possible that the display unit needs to be replaced. Cheers
Answer to: Why will it only stay on if on chargeLook up a guide on this site and replace the battery. Batteries only last for so many recharges. In the future, good battery practices are to allow it to run down to approx. 15% and then fully recharge it before using it again. This will help your next battery to last longer. Cheers.