Hi,
If you lost ILOM password on Exadata compute node, then you can reset it as below.
[root@veridata01~]# /opt/oracle.SupportTools/ibdiagtools/verify-topology
[root@veridata01~]# ibhosts
Let me change it to welcome1. Log in to compute node as root user and issue following command.
/usr/bin/ipmitool user set password 0x02 welcome1
Talip Hakan Ozturk's ORACLE BLOG 