Weak batteries, loose wires or a faulty console can cause a dim console display.
In an elliptical that uses batteries to power the console, replace the batteries to restore brightness to the console display. Replace the batteries during routine elliptical maintenance. If the display doesn't get brighter after replacing the batteries, you'll likely need to replace the console.
If the elliptical has a power cord, unplug the elliptical and check the power cord wiring connections to the console. Reconnect any loose wires. If the power cord is damaged, replace it.
If the power cord and its wiring connections to the console are okay, then you may need to replace the console because the display is faulty or the console isn't sending enough power to the display.