Greetings!
As per last update I can understand that the controller is now detected.
Are you able to see the controller in Smart Storage Administrator now and do the drives show up as assigned since there is no logical drives created?- hope you have already taken data backup from the drives.
If the drives are not detected, please verify if you have the following cable kit installed. As per "HPE ProLiant DL80 Generation9 (Gen9) QuickSpecs" and link below as well, the cable is required if you are installing P440 on DL80 Gen9.
HPE Cable Options:
HP DL80 Gen9 LFF Smart Array P440/P840 SAS Cable Kit 779619-B21
https://internal.support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00025631en_us
Coming back to the POST issue, please try the following steps and see how it goes.
1. Set BIOS to manufacturing defaults. Steps on page# 128 of link below.
2. Set the Onboard controller to "Enable SATA AHCI Support" refer Page 47 on the below link.
3. Set Power Profile to Maximum Performance. Page# 77
https://support.hpe.com/hpesc/public/docDisplay?docId=c04398276
4. If the issue persists, please test the server with only the P440 controller (without any PCIe card installed).