By step 11 a The Tablet turns of and reboot, but not in TWRP. The Screen is black and nothig happens (the backlicht is on) . Do you have any Ideas ?
I have exactly the same problem. Yes, you are in TWRP, but for some strange reason, the tablet thinks that it is connected to HDMI. If you can manage to connect to an external monitor via HDMI you will see the TWRP screen.
I also have the problem, but the HDMI screen is not usable, as I can’t see the lower part of the screen. Finally I could flash the rom by repeatedly booting to recovery ( fastboot boot instead of fastboot flash), until it showed correctly in the tablet screen (maybe it was because I was touching repeatedly the tablet screen an buttons, maybe it just works once in a while)
