Debugging these situations can be more about being methodical than about special knowledge. It seems like you've got several potential fault points: (1) card being flashed correctly; (2) card being functional; (3) card being recognized by OS; (4) working SAS cable from HBA to backplane; (5) SAS cable plugged into correct port on backplane; (6) SAS cable fully plugged into port; (7) backplane powered correctly; (8) backplane functional; and (9) drive functional.
Seems like (3) can be removed from the list based on your report. For (7), the 846s have six MOLEX power connectors that you can confirm are tightly connected but the drive lights coming on suggest that is probably OK.
You can also remove (1), (2) and (9) by plugging a breakout cable from the HBA to the drive and showing that your HBA can communicate with the drive. I would do that first so that you have a foundation upon which you can build for further testing.
The 846-SAS2-EL1 backplane has three SAS connectors - I don't recall their individual functions but that may be an issue here (5).
(6) On 826 boxes, I've had several experiences where the SAS cable seemed to be fully plugged into the backplane but in fact it was not so that led to some head scratching until I methodically walked through the list of issues above.
If you can report the results of these inquiries, we can try to debug further.