Usually when this happens (the LED's flash when the gauge turns on, and the display seems "on" but there is no data) it is an older gauge that has had it's service menu accessed and the contrast turned off by the user. This could happen on these older gauges if someone did not wait for the gauge to boot up and started hitting buttons. If they hit them in the right order the service menu would be accessed and then most likely the user would screw up the contrast trying to get out.
See this thread for details on adjusting it:
Aeroforce Technology Inc Technical Forums :: View topic - Screen lights up but no data
Otherwise contact
service@aeroforcetech.com. If we have to do this adjustment there will be a charge. If there is an actual problem with the gauge and it still meets the warranty requirements there will be no charge to fix it of course.
Todd