Hi I just wanted to give some feedback and I hope it helps someone,
I just recently tried to do a firmware upgrade on my nuc ( NUC5i7 RYBDWi35) and it didn't work, i got either completed successfully messages without a bios being updated at all.
once i got a message that the bios could not be updated as i had a 'legacy bios' and doing it via the F7 just rebooted and did nothing.
I disabled my secure boot and tried again and it applied the bios successfully
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