Unit will not power up. Voltage check indicates 12.5 volts to plug. Plugs clean. Unit was idle for several months. Removed unit from boat, and mashed power button dozen times, listening, and feeling for switch activation. Replaced power plug and activated power button. Unit powered up. Switched unit off, and have not been succesful getting unit to power up again.
had same problem. the cause was corrosion in the boat wiring. the power wire was corroded 95%thru. there was enough voltage to start the unit but when the sounder kicks in the voltage dropped below minimum and the unit shut off. took a LOOOONG time to find.
SOURCE: lowrance 330c gps unit
A "soft reset" can be accomplished by pressing and hold "Pages" key and press and hold "PWR" key till USA map comes on , then release both. A "hard reset" requires press and hold both "Z in" and "Z out" buttons and press and hold "PWR" button releasing all three when USA map appears.
Usually answered in minutes!