Hello,
It is unclear whether you mean the controller LED or the SAS host port LED.
For the SAS host port be sure the cable is seated firmly. You may need to inspect this closely as sometimes the cable is mostly inserted but is not all the way pushed in and fully connected.
There is more information about the LEDs and their variouis activity status in the MSA 2040 User Guide: https://support.hpe.com/hpsc/doc/public/display?docId=c03792322
Reference page 14 to start.
Cheers,
Shawn
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