At the point where Setup Entry/Boot would be in the normal boot path, the BIOS will display the following prompt and wait for a keystroke:
[ESC] Normal Boot [F2] Intel BIOS [F4] BIOS Recovery [F7] Update BIOS [F8] Operating System Recovery [F10] Enter Boot Menu
Please try the F8 in order to attempt to recover the Operating System on your Intel® Compute Stick.
Please confirm if you have a Windows* Image in order to restore your Intel® compute stick Operating System?
Did you create a Create Windows 8.1 recovery media prior to upgrading to Windows 10*? Although, this is optional, it is highly recommended. You could get more details on how to perform this task from here https://communities.intel.com/servlet/JiveServlet/previewBody/25142-102-2-30009/Windows10-upgrade-instructions-v2.pdf
Additionally, you could use Windows USB/DVD Download Tool - Microsoft Store * or Create installation media for Windows 8.1 - Windows Help
If issue persists and no available recovery media, I suggest to Contact Support
*Other names and brands may be claimed as the property of others.