Try adding a HDMI dummy plug. Older Intel NUC’s (8th gen and earlier) have an issue that’s fixed (but always seems to come back…) where they don’t like functioning headlessly (without a display connected.)
Edit: Also, make sure your BIOS is uptodate.
Do a BIOS recovery using the jumper. You’ll have to go to download the recovery BIOS from Intel.
Page 52 and 53: https://www.intel.com/content/dam/support/us/en/documents/boardsandkits/D54250WYB_D34010WYB_TechProdSpec.pdf
Edit: didn’t read the full post. You can turn off the other LED in the bios.Youll need a display to know what’s going on and to debug. If no storage is present, it usually boots to PXE boot or a screen that says no boot device found.