If a server does not complete POST then depending on the issue, it sometimes may not even get past to allow configure the hard drives into RAID array.
More information such as the server model, the error message(s) if any during POST, the LEDs illuminated on the server’s front panel etc., and if the server can be reached through iLO, then check if there are any error messages logged therein.
Also, if any hardware component were recently added, then reseat it, if not remove it and check. Reseating internal all internal components with the exception of the processors could help.
If the error message is about the array controller, remove the cache module, if installed, and check if completes POST.
Detailed information about the errors server model and configuration could help in providing a suitable recommendation.
Regards,
Vijayasarathy