Aurora R10 board uses Dell proprietary power switch embedded in led controller.  You would have an easier time using non-Dell modern ATX or microATX motherboard from MSI, Gigabyte which use standard 9 pin front panel Pwr sw c/w A51 R2 FP cable.
Having just gotten an Area-51 R2 system. I wonder if the chassis can have a new motherboard fitted to it ala Aurora R10 or newer footprint motherboard?
Area-51 R2, motherboard query