[Windows 10, 8, 7, XP etc.] ciccillover:
After reviving the tablet, here's my (successful) attempt at installing a clean Windows 10 OS (I chose Pro version, while at it). Posting it just because it's a different (and IMHO the cleanest possible) way to do what has already been accomplished. Please note that this procedure could theoretically also apply images from any other Win 6.* operating system (even Windows 7 or Vista), and even Windows XP with some major corrections. I doubt they'd work anyway, because this tablet lacks CSM, and even if it didn't, you would end up in troubles because of the missing drivers.

DISCLAIMER: this is how I did it, but can't guarantee it will work for you. There are many things that can go wrong in such a long and complicated process (20 step!), so if you don't feel at ease with it, if you are afraid to make your tablet unbootable or if you wouldn't be able to recover it on your own in case anything fails or there's a mistake in my procedure, please stop right here. If you choose to follow these steps, do so at your own risk. I can't be held responsible for anything that may happen because of that. You have been warned.

Requirements:

- tablet fully charged

- development machine with an internet connection, about 10 GB free disk space, preferably running Windows 10 (version doesn't matter)

- OTG cable

- powered USB hub

- USB mouse and keyboard

- USB pendrive (at least 8 GB)

- Rufus (here)

- Win10PE SE (here)

- Windows 10 x86 ISO image (use whatever version you prefer, but x64 won't work as this tablet has 32 bit UEFI, and make sure it's smaller than 4 GB - can be done with larger ISOs, but then additional steps are required)

- WinNTSetup3 (here)

- drivers from Trekstor SurfTab Wintron 7, which is another clone of this tablet (chipset, sensors, video, audio and others - WiFi if needed (not in my case) - touch panel)

Preparing a Windows 10 PE live OS image:

1) extract Win10PE SE to %systemdrive%\Win10PESE (use this path, extracting to the desktop or any other folder under %systemprofile% won't work, rest assured)

2) extract the Windows 10 iso of your choice under %systemdrive%\win10 (mounting as an ISO won't do the job, you need to extract it)

3) start Win10PE SE by launching BuilderSE.exe, point it to where you have extracted the Windows 10 iso by clicking "Source". Leave everything else as is, or fiddle with the other settings at your own risk. Then click back on "Script"

4) in the left hand pane, select Main configuration and choose 800x600 4:3 (to make sure nothing is displayer beyond the 600 pixel vertical resolution of our tablet)

5) if your Windows 10 ISO has multiple editions on it, on the left hand tree jump to Images configuration, click Choose your image index and select the desired image index (again, make sure it's 32 bit, not 64), otherwise skip this step

6) scroll down to Utils in the left hand pane, expand Extract WIM folders and launch that script by clicking Gooooo (this will extract the install.esd image with the chosen index to a temp folder on the hard drive, in a command line window)

7) once finished, the default parameters are just fine, you can leave them as they are or customize every other aspect. Whatever you choose to do, click the Play symbol in the upper right corner. You will end up having a UEFI bootable, x86 Windows 10 PE iso in %systemdrive%\Win10PESE\[something].iso. In theory Win10PESE can already put the iso on your pendrive, but in my case I found that Rufus worked better)

Preparing the pendrive:

8) insert the pendrive on the development machine, start Rufus, select your pendrive on the topmost dropdown menu, then click the CD icon next to the dropdown menu that reads ISO Image and select your ISO. Make sure that Partition scheme and target system type are set to MBR partition scheme for UEFI (GPT should work too, but I haven't tested) and filesystem is set to FAT32, then click start. You will end up with a nice x86 Windows 10 PE on a UEFI bootable pendrive that you can still use in a number of other situations, for data rescue from an unbootable machine for example

9) extract WinNTSetup to the development machine and launch the x86 version (doesn't matter if your development machine is running an x64 OS, launch the 32 bit version). It will ask to download a few tools to it's own folder, let it do that (don't worry, these are mostly tools from Microsoft and won't affect the development machine anyway), and close the program when finished

10) extract each drivers to its own folder

11) copy the WinNTSetup folder (not the zip file, because we need the tools that it's just downloaded to its folder), the drivers from the TrekStor clone tablet you have just extracted and the Windows 10 install.esd (if you followed my steps, it should be in %systemdrive%\Win10\sources\install.esd) to the root of the pendrive

Booting the initial setup environment on the tablet:

12) insert the OTG cable on the tablet, plug the USB hub and its power adapter, plug the keyboard, mouse and pendrive to the hub

13) on the tablet keep VolUP pressed. Press power for 5 seconds then release it but keep VolUP still pressed. A graphical choice menu will pop up, select boot manager and select your pendrive (should be the second option). Allow Win10PE to boot

14) when in Win10PE, format your C: drive. While at it, you can get rid of the extra partitions if you want more space, as long as you leave your EFI and system partitions intact. Personally I only had one 450 MB partition at the end of the drive, and no 5 GB recovery partition. I have deleted anything that was beyond the C: partition and it's running trouble free

15) go to the pendrive and launch WinNTSetup. Select your Windows 10 install.esd in the first box, leave Z: (or whatever it calls that, it's an automatic procedure) as the location of the boot drive and select C: as the location of installation drive. You can optionally install to a VHD (multiple setups anyone?) but I don't recommend it.

16) click setup, leave everything as it is in the next window (unless you know what you are doing) and let it install. You will receive a confirmation that the setup will continue on reboot. Shutdown the tablet, unplug the USB pendrive.

Windows 10 second stage setup, drivers and optimization:

17) start the tablet. Let the setup finish, use your keyboard and mouse (touch panel not working yet)

18) as soon as it's finished installing, replug the pendrive and install the drivers in the following order:

- chipset, audio, video etc [reboot]

- touch panel [reboot]

- WiFi if necessary (check in device manager if there is a yellow exclamation marks on an unknown device) [reboot not needed, but recommended]

19) not mandatory, but will help recover some more free disk space. Perform disk cleanup including system files, then open a command prompt (run as administrator) and execute:

compact /compactos:always

20) unplug everything from the USB port, plug in the charger and let it finish.

Done! :)

Hope this helps. If that's the case, hit thanks or consider donating