You can power the CEC on using your HMC interface.
To power on the CEC, select it in the contents area and choose Power On. The HMC asks you select a Power On mode from a list of modes. The following is a description of those modes:
System Profile
The system profile power on mode boots the system according to a predefined set of boot instructions. For instance, these instructions might tell the HMC to boot the system in a certain Full Machine Partition power on mode.
Full Machine Partition
The Full Machine Partition power on mode allows you to use all of the machine's resources on one image once the machine has been powered on. This is the traditional, non-LPAR method of using your machine's resources.
From here, you can choose traditional power on options. The following is a description of each:
Power On Normal
Power On SMS
Power On Diagnostic Stored Boot List
Power On Diagnostic Default Boot List
In this mode, the system attempts to boot from the first device of each type found in the list. It does not search for other bootable devices of that type if the first device is not bootable. Instead, it continues to the next device in the list. The system's firmware supports up to five entries in the boot list. The default boot sequence is:
Partition Standby
The Partition Standby Power On mode allows you to begin the partition
creation process. Use this mode if you want to create more than one partition.