For reference, I am using the factory image I posted way back on page 5.
A few notes about the installation:
1) Magisk Manager does not work with the stock File Manager
-When you go to patch the boot image, Magisk Manager crashes
-I rebooted my device and installed "File Manager" (the ASUS one, but shouldn't matter) from the play store
-Next I force-stopped Magisk Manager
-Finally I re-opened Magisk Manager and was able to select my boot.img to patch.
2)Start.bat file in Root.zip points to the wrong zip file, so after you add "patched_boot.img" to the archive, rename the archive from"6521_1_input.zip" to "input.zip".
-Alternatively you can just change the single line in the batch file to the correct filename
If anyone's interested I can probably type up a longer step-by-step howto and post it tomorrow.
Since this a one of those things that people wanted , I am going to make a new topic to give full details...
You have to be rooted first..then go to the root directory, them oem folder, them in the config.txt you will see a line (i forgot exactly ) but something like..com.fyt.bt = "1"
set it to "0"
and then save and reboot.
if you have the new latest updates, the bluetooth setting in the android menu will disappear (at least on mine it did).. you can use a third party tool to show the bluetooth setting if you want to see and pair devices from there.
Or you can just use the conventional way .. (the default bluetooth app )
on the 4pa forum, I read if setting it to 0 doesn't work you can try different numbers up until 5.
Please give it a show and let me see if it works for ya.
So it is config.txt in /oem/app and the value is "sys.fyt.bluetooth_type=1".
For those who are rooted they can follow @ojuniour method.
For those who are not rooted (like myself as I don't want it): That is also a very simple action. (Edit: and also rooted users can use that method)
Unzip attached zip file to a clean USB-stick. It only contains the config.txt and lsec6521update. Use this to flash your device. It will be a superfast flash only updating the config.txt (please don't fear the maybe scary messages about "resetting to factory defaults". I does not do that, it is just a message from the flash program for a "normal" flash).
It is actually the exact same approach as I described in "Modding your Joying/FYT SC9853i unit without root" in the first 3 posts.
The config.txt contains the value "sys.fyt.bluetooth_type=0". Simply replace by 2-5 if it doesn't work and flash again, like described in the 4pda topic@ojuniour referred to (Thanks again for that).
Note: After reboot I took my bluetooth keyboard in the car and tried to connect with the BT app. It did find the keyboard and wanted to link it, but stayed on "linking", without actually linking.
So I installed "Bluetooth Pair" from Waylon Huang (simply the first in my search in the play store) and with that one I could successfully pair my BT keyboard (and type 10x as fast as with the onscreen soft-kyboard)
I have downloaded and examined the files by checking crc sha-256 and all of them identical as 14-08-2019 update except Stm32ud.bin file which is mcu. So no need to download again 1gb update file for update. Just extract below attached file and put them in to the usb then unit will update itself without loss of data. You can keep all the settings without losing anything.
Normally joying should advise above procedure to prevent unnecessary loss of time instead every time advising full update but i already lowered my expectations