Actually it's on page 34:

Power
To turn the Model 990 on:
1. Press the MAIN POWER button on the unit’s rear panel.
The Standby/On indicator on the front panel will glow yellow.
2. Press the STANDBY button on the front panel, or any source
button (such as DVD, VIDEO 1, or CD) on the remote control.
The Standby/On indicator will turn blue, and the front-panel display
will illuminate.