Hello TangIT, Are you trying to set the management IP through SMCIL or are you using the serial cable to try & set the management IP?  Also when you are trying to set IP does it let you put in the IP address, Subnet mask & gateway then give you the error or does it gives the error right after the IP address is put in?  Please let us know if you have any other questions.
I get the following error when I try to set the Management IP address of the RAID Controller 0 Return code: Error 4 - The operation cannot complete because of an incorrect parameter in the command sent to the RAID controller module. Please retry the operation. If this message persists, contact your Technical Support Representative. Operation when error occurred: PROC_setEthernetInterfaceProperties  Regards
Dell MD3620i Raid Contoller Module 0 Management IP Error