I am assuming you meant Motorolla MC3090 mobile comupter running Windows CE.
MC3000 User Guide -
Motorola MC3090G Win CE 5 0 Core User Manual
On 28, 38 and 48-key keypad configurations, press the Power button to turn on the mobile computer. On 20-key
keypad configurations, simultaneously press the Fn and MENU buttons to turn on the mobile computer. If the
mobile computer does not power on, perform a
cold boot. See Resetting the Mobile Computer on page 2-28.
When the mobile computer is powered on for the first time, it initializes. The Splash screen appears for a short
period of time, followed by the Calibration screen