All the firmware and files are in a microsd card situated inside the device.
The issue that you may face (and many others have) is that sometimes when it crashes (and if it was somewhat writing to the card) it can stop the device from booting or cause some other issues. However based on your description, it seems the device is working, but the screen is somewhat not working well.
If you wish to take a risk and void possible warranty, you can..
Open the device (be careful, there is a ribbon cable between screen area and motherboard)
Take out the microsd and place in a pc memory card reader/writer
download the firmware from herehttps://drive.google.com/file/d/0B0wz_n5he9GpQW96allVTUJNSnM/view
then use a tool such as win32 disk imager to write this firmware back to the microsd card.
Then place the microsd card back into the papk3 plus device and put everything together.
If you still are facing issues, then its more than likely a hardware issue I am afraid.
edit: at one stage, when I rebooted, no games or icons were visible. Rather than to open the whole thing up and rewrite the firmware, I fixed it (success varies) by doing the following
Turn papk3plus off.
connect to usb and pc
turn papk3 plus on
wait a while
Try to access the drive (fat32 partition holding the games). When windows asks if you wish to fix the disk, select yes.
remove usb cable after and reboot
This brought the icons back, but again, depends on how much corrupted the file system is