Hi there,
I just wanted to update my findings so far: I've tested the pins and got it working. Because it's quite similar, maybe you might have also some luck.
The other end of the power cable of the backplane is a 5-pin cable (at least in my case).
When you turn the 6-Pin End to you and with the header clip to the right hand side, the first pin on the upper right corner might be free:
View attachment 28692
The other end is a 5-pin connector. In my case, I've connected it via a custom cable to a standard ATX 4-pin molex connector on my power supply (simply cut whatever there is on the other end and apply dupont male connectors on it). For this, I've used the following pinout:
1: 12V
2: GND
3: 3.3V (or empty)
4: GND
5: 12V
With this, on my Gen10 normal Backplane, the drives are spinning and working just fine.
In my case I have installed it in a Streacom DB4 housing:
View attachment 28693
As you can see, I don't have the HPE SAS controller, so probably that's why the lovely lights aren't on. At startup, they shortly blink up in a row. Maybe there is a good Linux package to enable this feature again?