I got called out on a little 40 ton air cooled trane (lost the M# so bear with me) that is 2 years old. the unit would not operate and the touchscreen was blank. so after checking everything I could i pulled apart the screen and in the process the unit started working. after looking things over i decided the ribbon cable between the two boards was the problem. I pushed the cable into place but the screen is so dark that i can hardly read it. so my question is this, is the ribbon cable bad or the screen? or am I heading down the wrong road alltogether?