Thanks to alecxs for all the help. In the end this was possible with Magisk Manager and odin. I will try and list all the steps needed, but there was a lot of trial and error so I may miss somthing.
- Get enable OEM reset then usb debugging (this will factory reset the
tablet)
- Find the stock boot.img I found mine here
- transfer the boot.img to your phone and install magisk manager apk
(you will have to enable installing from unknown sources)
- click install magisk and choose the option to patch a boot file. Copy the
patched file back to your computer
- rename the file back to
boot.img
- download this tool to repackage it to a .tar.md5
file
- copy the boot.img into the parts folder and try and make
the .tar file then try the .md5. if you have problems download the
latest version of cygwin64 and copy the contents from the
installation folder into the bin folder of the tar.md5 tool and try
again
- now you should have a tar.md5 file containing your patched
boot.img that you can flash onto the ap partition with odin. restart
to boot loader ( hold down power and volume up or use adb command
adb reboot-bootloader and flash (there are other more detailed
tutorials on how to do this)
- check to see if it succeeded. For me
it succeeded and then when rebooting it failed the integrity check
and factory reset itself. I reinstalled magisk manager and found
that it had worked. I let magisk install itself and update. I
installed a root checker and it showed i had root access
I hope this helps someone