It really reminds me of the situation we had a few years ago for HP Probook. I installed OSX on it for my husband but he wanted to go back to Linux. What I did not realize was that I inadvertently enabled Fast Boot and unable to go into BIOS.
We ended up a house call of "specialist" who managed to get into BIOS and disabled Fast Boot. It was a 60 Euro lesson I learnt 
Searching Fujitsu forum, I hit this thread:
https://forum.ts.fujitsu.com/forum/viewtopic.php?p=151855
The last comment by Fujitsu moderator might be helpful:
If that doesn´t work, you can press the F2 key first and then switch on the device while the F2 key remains pressed.<<




The shipping cost was also covered by the manufacturer.