The home switch is bad.
Test the incline and if the unit elevates, check the home switch with an ohmmeter.
Incline test is performed by first turning the unit OFF at the power switch. Then, while pressing the INCLINE DOWN key, turn the unit power switch ON. TEST MODE will appear on the display. Press the INCLINE UP key to start the elevation. The unit will only elevate while the INCLINE UP key is being pressed. End the test by simply turning the power switch to the OFF position.
Ohmmeter test should show the home switch open at one position and closed at the other. Replace the home switch if necessary.