Marc,
Could you try a BIOS update to the latest version 26? Since you don’t have video, you could try the update by using the BIOS recovery method. (Remove the BIOS jumper complete, save the .bio file on a thumb drive and turn on the system) https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=23926&lang=eng&OSVersion=%0A%09%09%09%09%09%09%09%09%0A%09%09%09%09%09%09%09&DownloadType=BIOS