Hello, just to let you know I have solved it..
I managed to get hold of an original Keypoard for it...
After docking the keypad, I could get into the BIOS as usual ( Hold Power Down and Volume down on the tablet )
Connected the off board DVD with Win 8.1 to the mini USB on the side of the tablet.
Restarted it and it did no find the DVD and the screen prompt was saying error with windows, insert disk ( or words to that effect )
Then I noticed there was a full size USB socket on the side of the keyboard
I connected the DVD to that socket and restarted
Same problem
Rechecked the BIOS
Noticed that the BOOT list was - Windows Boot manager selected or Disabled
So I disabled the Windows boot manager and saved the setting.
Restarted and it then found the DVD and installed Windows 8.1
I then decided to install Windows 10 and after finding the various drivers all OK.
There is a lot more info I could add if needed
Regards