Hi Daniél,
I used the typical tools to open mobiles, tablets, etc… and I started from the bottom, placing the tools that is like a guitar pick between the screen (white part) and the rear (metal part). Then I moved the pick to open the tablet from that part to one of the sides, then from the bottom to the other side and the top part just disassembled because the other 3 were already done. I was not too careful and it opened fine, no cracks at all. The battery and mainboard are attached to the screen side, so the rear can be easily removed because it hasn’t got any connection.
This is the second time I have to open the tablet (the first one was to check the micro-sd reader, but I could not fix it) so maybe this time was easier (I don’t remember the first time xD).
Hope this helps!
J