Recently on booting a Xseries IBM x3650 server the following error was diplayed on the bios and the server would not start

Fatal Error : Controller monitor Failed. Controller now started

This is an error on the onBoard raid controller. Reseating the memory and unplugging and plugging in the battery did not help.

In the end we had to swap the whole mainboard out. The metadata for the Raid drives is stored on disk so no data was lost