Funny you mentioned that, Bigus, I got to feeling "lucky" so I decided to do a nice clean install after the upgrade... Was a lot more work, it's not for the faint of heart! Feel better about it though,
but still missing one driver at present - FIXED with DriveForLife's help!.
Don't try this unless you're reasonably techy with experience!!0) You will definitely need a USB keyboard and mouse, and likely a USB hub to connect both at the same time! I used the microUSB port for power, but then I had to use it to boot off my USB memory stick! The touchscreen mousing drivers are not likely to be included with Windows 10 and popup keyboard might be flaky even after!! My tablet is nice in that I have a 2nd full size USB port, and a microUSB port which is normally for power.
1) First do the upgrade with the popup Windows app normally! This will associate your product key with 10. After a full upgrade, if it works reasonably well and all drivers are accounted for, then you can try for a clean install! I hadn't used my tablets long enough to care too much about established settings and apps, so I didn't care.
2) If your system has no Windows product key sticker, then it's embedded in the BIOS or the UEFI partition by the OEM, etc. It's also stored in the Windows registry in binary form so you need an app to decode it to readable form - a link to one that works is below! Write it down because on a clean install it'll ask you for it and not find it on some custom partition.
http://www.nirsoft.net/utils/product_cd_key_viewer.html#DownloadLinkshttp://www.nirsoft.net/utils/produkey.zip3) For tablets with restore options, you'll have to make a decision about the ~4GB of space that was allocated for a clean copy of the original OS! I deleted that partition and joined it with the main one for a full 28.9 GB of space - My WinBook TW100 is a 32GB tablet! Only 100 MB is allocated at the start for the UEFI. So yeah, the Windows installer gives you a basic Partition Manager screen for deciding where to install it. You can delete/create/format/etc. It'll likely refuse to touch the custom reserved partitions as it did for me. (I wasn't feeling THAT lucky to research other fan software or maybe Linux to nuke that UEFI and upgrade it to 64-bit - don't need to risk bricking my tablets!)
4) Download "Win10_English_x32.iso" or "Win10_English_x64.iso" from Microsoft. It will ask you for edition, choose the FIRST one, "Windows 10" (the others are hacked versions for Europe due to their crazy money-stealing legal courts!), then choose language as "English" and you should get buttons for 32-bit or 64-bit.
https://www.microsoft.com/en-us/software-download/windows10ISO5) Making a bootable 4GB (or more) USB memory stick with a Win10 32/64-bit ISO was easy enough with an app called Rufus.
https://rufus.akeo.ie/a) First you browse for the Win10 ISO, "Win10_English_x32.iso" or "Win10_English_x64.iso"
b) Select MBR partition scheme for UEFI
c) FAT32 (default) for File system
d) 4096 bytes (default) for cluster size
e) MAKE SURE to type something short for volume label like "WIN10" - if it generates its own long one, it might error out on formatting and not tell you why it failed.
f) All other settings leave to default
With your USB memory stick plugged in, it should've detected it and pressing the "Start" button will begin. If it succeeds, your memory stick will be load with win10 and be bootable.
6) Booting off a memory stick for a tablet could be tricky... I HAD to use the microUSB port, so I needed a male microUSB to female full-size USB cable to plug the memory stick in! This means I had to rely on the battery of the tablet since I couldn't have the power cable connected to it!
But before that, you need to change the BIOS Boot Order! You can do this 2 ways! Windows 10 can do it for you in Settings or you can use one of the F keys when you turn your system on with keyboard connected (mine was F2)! On Windows, click the new start menu, hit Settings -> Recovery -> "Restart Now" and that'll take you to a menu to "Use a device" where you will choose "USB HDD." So Windows will change the BIOS order to boot first off a USB memory stick before the internal flash drive and that should do the trick!
7) THE REALLY BIG PROBLEM: You need to copy your existing "C:\Windows\System32\DriverStore" folder as one way to *help*, find driver detecting and installing apps as another way...
a) Here's one app that found 2 drivers for me:
http://drp.su/This one is also freeware:
http://www.drivethelife.com/free-drivers-download-utility.htmlb) In my case, Intel made many driver installer programs that you have to find for things like the camera, microphone, speakers, etc. I got it from this link:
http://support.lenovo.com/us/en/downloads/ds040016Now everything is working,
except I only have one unknown device driver and I don't know what it is just yet... So this MAY or MAY NOT work out well for you, it's a tad risky and it puts you in the same situation as upgrading an Android tablet/phone, you need to research a bit simply because a clean Win10 install will not have ALL of the drivers in it for every known piece of hardware out there... Microsoft just isn't that good and even the Windows Scan/Update feature will not detect everything and find a driver for it, etc.!
Additional Info for Drivers:
http://answers.microsoft.com/how-to-install-and-update-drivers-in-windows-10/Conclusion: If you're not a techhead, just stick with upgrading. All Win7/8.1 drivers present are imported, upgraded if a Win10 version was created, and things are just more likely gonna go smooth! If you're like me and got to feeling lucky plus have experience in this, then give it a shot, but FAIR WARNING!
EDIT: With the help of
http://www.drivethelife.com , I was able to determine what the final device was! It didn't install a working driver though, so I grabbed the files from a Win8.1 install, picked the correct INF file and installed over with the Device Manager. This concluded my full upgrade and everything is now fully working and looking in order! It looks like this software is what you need, it can backup important driver sets such as from Intel, and you can save that on your USB memory stick for a clean install attempt.
Either way, good luck should you attempt this yourself!