There are 2 utilities you can use.
hpeoncfg - can run on the local server OS and can manage ILO
hpqlocfg - can manage ILO remotely
First you need ILO make work again, otherwise you cannot do anything except replacing the system board.
Shut down the server and pull the plugs.
Connect the power cords again and check if ILO is alive. If yes, capture the ILO diagnostics web page and post.
Once ILO is alaive, update ILO firmware to 2.55, if older than 2.42.
Then use hpqlocfg to execute the following XML file
<!-- RIBCL Sample Script for HP Lights-Out Products --><!--Copyright (c) 2016 Hewlett-Packard Enterprise Development Company,L.P. --><!-- Description: This is a sample XML script to force format ll --><!-- the iLO partitions. --><!-- iLO resets automatically for this operation to take effect --><!-- Warning: This command erases all data on the partition(s) --><!-- External providers will need to be re-configured if --><!-- partition is formatted --><!-- Input: VALUE tag: all - format all available partitions --><!-- NOTE:You will need to replace the USER_LOGIN and PASSWORD values --><!-- with values that are appropriate for your environment --><!-- See "HP Integrated Lights-Out Management Processor Scripting --><!-- and Command Line Resource Guide" for more information on --><!-- scripting and the syntax of the RIBCL XML --><!-- Firmware support information for this script: --><!-- iLO 4 - Version 2.42 or later. --><!-- iLO 3 - None. --><!-- iLO 2 - None. --><RIBCL VERSION="2.0"><LOGIN USER_LOGIN="Administrator" PASSWORD="password"><RIB_INFO MODE="write"><FORCE_FORMAT VALUE="all" /></RIB_INFO></LOGIN></RIBCL>
If you can the "success" message, pull the plugs again. Re-insert the power cords and check ILO log if the format was done.