My hitachi 58HK6100U has a blue screen but is giving sound

My tv screen is blue but i am getting sound. I watched a video on youtube & the tv had the same problem as mine. The guy checked the t-con board as 2 led lights were lit on it , he put a new t-con board on & 3 led lights came on. He checked the tv & the picture was there so my question is do all t-con boards have 3 led lights when they are working properly ??? ... just want to before i start stripping the tv down to check the backlights. My tv has a TC575-009 V1.0 t-con board in it , does it have 2 or 3 led lights on it ???