ok i have gone through this it is the battery.( to start you need a new CR3032 battery)
ok here is how to do it
1.Unscrew the back of your tama
2.then you will see 4 smaller batterys ,unscrew them
3.there might be some bits that fall out like the red connection thing,Battery and antenna
4.take that battery out and replace it with the new one and put all the bits that fell out back where they belong!
5.screw the four batterys back together
6.do the last one as well and make sure they are tight
7.reset and download
if there is a chunk of the screen missing take it apart and screw the screws really tight put it back together.
that should work