On the mainboard is a 2×3 6-pin header with a jumper where one of the center pin is missing.

• unplug power
• open case
• set RCV jumper
  • when the missing pin is at the top, bridge the two left pins with the jumper
• plug in power
• start system
• press F2 to get into the BIOS
• save BIOS settings
• shut down system
• unplug power
• put the RCP jumper back to its normal position
  • when the missing pin is at the top, bridge the center and the right pins at the bottom with the jumper
• close case

• obtain BIOS firmware update
  • you can download it from https://support.ts.fujitsu.com/IndexDownload.asp
  • I used a file called
    • D3543A1xAdminpackageCompressedFlashFiles_V50013R1140_1302609.ZIP
    • sha256sum 1c6b6acd8520d54f5e3ff8fa8030b7340c242ce051e065b16a13581e5b131125
• prepare a USB stick with a BIOS firmware update
  • MBR partition
  • FAT32 file system
  • extract downloaded ZIP archive and just copy all the files to the USB stick
• unplug all external devices
• unplug power
• open case
• set RCV jumper
  • when the missing pin is at the top, bridge the two right pins with the jumper
• plug in the USB stick in one of the two USB 3 ports at the front
  • it does not work with any of the USB 2 ports at the back
• plug in power
• wait a moment
• success is notified with a single beep
• progress is notified with many random very short bip
• afterwards there is a moment of silence
• followed by a pattern of beep - beep - beeeeeeeeeeep - beeeeeeeeeeep
  • the two long beeeeeeeeeeep at the end are very long both
  • they are the sign that BIOS recovery was successful
  • from pluggin in power to this point it did no even take 30s in my case, the manual stated 3-5min
• unplug power immediately
  • if you don't unplug power directly after the two very long beeeeeeeeeeep it restarts the BIOS recovery automatically (and you might not want this)
• remove the USB stick
• put the RCP jumper back to its normal position
  • when the missing pin is at the top, bridge the center and the right pins at the bottom with the jumper
• close case
• plug in power
• the system should boot again
  • first boot takes quite a long time
  • but it displays the Fujitsu logo quite early when it is plugged to a monitor, so that is a good sign

In the BIOS one can configure the BIOS to expose itself via the COM1 serial console instead of one of the Display Port outputs.

We found out that it is not possible to boot from a USB stick while the BIOS is redirected to the serial console.