Typically, the is an issue with the battery. Try turning on the device while it is charging. If this doesn't work, this means that your charging pin is faulty and is preventing the battery from receiving charge. If it does turn on while charging, this means that the battery is dead and needs to be replaced.
As said before, try updating your software to the latest release. Sometimes, there is an app or program installed that is conflicting with your internal hardware. Try removing recently installed applications and see if it fixes the issue. If it doesn't help, then you may need to reformat your device through the tablet general settings menu.
You will not be able to recover deleted files using the tablet. However, there are many 3rd party software that recover lost data. You will have to remove the SD card from the back of the device and connect it to your computer.
Like mentioned above, there might be poor ventilation or dust buildup inside the tablet. . It could also be a hardware issue; if the motherboard or CPU is faulty, it may mean you need to replace them. Try to locate exactly where the heat is coming from and work from there.