Epson ActionTower 3000 Computer User Manual page 22

Then turn on the computer by pressing the power button
located on the left side of the front panel.
The power indicator lights up. After a few seconds, the
computer performs its power-on diagnostics. This is a series of
checks the computer runs each time you turn it on to make sure
everything is working correctly.
If necessary, use the controls on your monitor to adjust the
brightness and contrast until you can easily see the characters
on the screen.
1-6 setting up Your system