Heh, I suddenly found that the failure to mount the partition /data occurs when you install TWRP on the tablet "out of the box", or if firmware has been installed in a standard way according to the Chinese instructions. If firmware has been installed by the script Mirek - TWRP works WITHOUT PROBLEMS.
I made version 3.0.2 - don't know whether it makes sense to replace the version 2.8.7?
If the device enters in dnx-fastboot mode, I can only advise you to reinstall Android and Windows. Android install only by Intel Phone Flash Tool with "blank" option.
DNX Fastboot Mode -> simultaneously pressing power button and both volume "+" and "-".If on startup I do power more volume down does nothing
DNX Fastboot Mode -> simultaneously pressing power button and both volume "+" and "-".
You and your friend need to think first about the return of the tablet to life, then about updating Windows. And priority installation for Android, Windows secondary. The fact that you can go into BIOS inspires some hope.
There's no need to reinvent the wheel. There are 2 ways:I would try to install the Google Apps but first I have to hear my friend cuz I'm afraid to do him a damage.
Do you know if there is any guide about that I could follow?
G4 or G3 revision? If G4, then any available firmware will do. With G3 harder - there may be issues with wake tablet from sleep.I do have a v7 model
Any firmware version will not make the tablet a brick. The only question is the presence of bugs: sound, sleep, overheating...I just thought I would do a nandroid backup/root first. But installing 0531 from the start somehow seems safer?