Dim Display problems are usually caused the by 1. a faulty backlight IC 2. Faulty Screen or a faulty logicboard not outputting the correct voltage, which stops your Apple Mac screen from illuminating.
Many companies tend replace the screen, this option is would turn out to be a expensive repair if misdiagnosed, where as we can replace the Backlight IC for a fraction of the price.
Over the last 2-3 years Retina screen have been widely used on all Apple Macs and if a wrong screen is fitted will end up Damaging the LCD Connector and the Retina Screen and the Backlight.
Therefore the fault lies with the logicboard, not outputting the correct voltage to the screen or the PCB on the Screen, which can be economically repaired.
Common Symptoms are:
Faint Windows Logo
Turns on and Windows Login Sound is Present but nothing on screen
