Just got this newly-wiped Precision M3800.
Trying to use OS Recovery tool to download the Windows OS: enter the correct service tag and choose the OS (Windows 8 - only option) to download, but as soon as the download starts get the message -
'We encountered an issue downloading your image. Please click the retry button to try the download again.'
Have retried several times: on my old Inspiron laptop and on a different, non-Dell, desktop machine (both running Windows 10).
Cannot try on the M3800 as it has no OS at all ATM.
No changes to anything here, but on retrying the same download today, it has worked.
So now to burn Windows 8.1 to USB...
and finally, try to get the Windows 10 upgrade to work.
Wish me luck!