You may have the same problem: iPad work well, but the screen is black suddenly; or it is charged in the night, but can not be turned on next day. How to find the problem and repair quickly? (certain that iPad is not fall on the ground or into water)
Use a good charging cable to charge it, to see whether it has the charging prompt. If yes, just wait charge until it has enough power to work. But focus on, long time no use and power off can cause iPad is charged normally, but without the charging prompt, because it makes the battery in starvation status. In this case, need to charge it with 2A charger in an indoor above 10 degrees. If certain that is battery problem, just change it.
DFU Mode Problem
1: if yes, just wait until turn on;
2: if no, please connect with computer to restore and update it (computer need to be downloaded iTunes). If it can not be connected with computer and update, it is the screen or mainboard problem.
Neither battery problem nor DFU mode problem, can not connect with computer to restore and update as the above, need to disassemble it for checking the screen problem and repair.
Firstly, connect a new screen to check the mainboard, if the new screen can work well, means that the mainboard is no problem, just the screen problem. Then put iPad under glare, if the screen is light, means that is the black-light problem. Find a good back-light flex cable to connect on the control panel of screen to check again, if the screen work well, just need to replace the black-light. If under glare, the screen is still black, it is the problem for control panel of the screen, need to replace the whole LCD screen.
Secondly, when new screen is connected the mainboard, the new screen is also black, means that mainboard has problem, need to repair mainboard firstly. After repair the mainboard, the screen still can not work, just check the screen problem and repair as the above.
In other word, if the problem is not solved as the above, or you are not professional repairer, please go to Apple official office to enjoy warranty.