With a fresh battery(s) installed, try performing a “manual restart” operation to bring the LCD display back to life. Do this by pressing all three buttons (Mode, Start/Stop, and small, recessed Set button on front or back, depending on model) at once, and then releasing all three. Or, if your computer has an ”AC” button, press and release the AC button to perform the manual reset operation. This should bring the LCD display back to life, and the unit can now be re-calibrated for your bike.