[General Questions and Answers] Hash.H:
Thanks to [MENTION=4821597]social-design-concepts[/MENTION] , we are now able to access the UEFI Setup on the Lenovo Tab S8-50; In order to do that, you must first follow these steps:

Requirements :

1- A Computer, preferably windows.

2- A micro USB cable to plug the Tab into the computer.

3- You must have the proper ADB drivers installed.

Steps:

1- Make sure your Tablet has been rooted, and has at least 50 % battery life just in case.

2- Plug in your Tablet, and you should see a window open up on your tablet, which says to either connect as a Media Device, or a Camera. Make sure to check the Media option. Make sure to also check the box that says USB Debugging.

3- Once all those steps are completed, you must download the attached ADB file suite I compiled from the Android Developer Kit. It has no virus so don't worry.

4- Once the files are download, and you are sure your tablet is connected, extract the files to your desktop.

5- Open the up the extracted folder, which should be named as "adb", and press the Shift key on your keyboard, and right click anywhere until you see "Open command window here" option in the drop down menu.

6- You should see a command prompt window appear which says " c: \adb > "

7- you want to first type in " adb push efibootmgr32 /data/local/tmp/efibootmgr " without the quotation marks obviously.

8- Then you want to type in " adb shell "

9- If you did the previous step correctly the command line should change to " shell@S8-50F:/ $ " or something like that.

10- After seeing that message, you want to then hit the space bar once after the $ sign and type in " cd /data/local/tmp "

11- Then it should look something like this " shell@S8-50F:/data/local/tmp $ "

12- Simply type in the word " su " and it should change to " root@S8-50F:/data/local/tmp # "

13- You then need to type in " chmod 6755 efibootmgr " after the pound sign, just make sure there is one space between " chmod " and the #

14- Then, like the previous command, make sure there is one space between the pound sign and the command " ./efibootmgr -? " and once you type that in, you should see a long list appear.

15- Then after that you want to type in with the space between the # sign and this following command " ./efibootmgr -v "

16- Then you want in " ./efibootmgr -n 0001 "

17- Finally, you need to type in " reboot -p "

18- This will reboot your tablet, but you must manually turn it back on.

19- You will see a long list of random commands in yellow and white flash on your screen.

20- make sure you have a powered otg usb cable powered by a separate power source other then your tablet in order to connect a keyboard

21- Once that is plugged into your tablet, type in " exit "

22- you should be greeted by a white screen with a blue bar on top and a bunch of commands.

22- That is how you access the bios.

- You now have the option to modify many other options, such as disabling fast boot in order to install windows, allocate more gpu memory and so on.

- here is the link to the original link where you get a better view as to what the commands should look like.

http://xdaforums.com/general/general/lenovo-tab-s8-50f-stock-firmware-rom-t2989791/page71

Hopefully this works. NOTE: I am not responsible for any damage that may be caused to your device.