samsung un40h5203afxzc doesnt power up flashing power led

[ronl]

Hi Members I have a samsung un40h5203afxzc that.doesnt power up.power led flashes.I checked the voltages on the power board for the main board and all checks out. I'm hopping its not the backlights. It uses power board number bn44-00769c. I thought I would test back lights but pin markings on connector cnl802 is confusing. Pin1,2 = d+.pin3=s2-,pin4= s2+,pin5=n/c,pin6=s2-,pin7=s3-,pin8,9= d-. Power for backlights on power board are marked 151.8 v at 425ma.not sure if I should hook up external 151.8 v power to pin1 for + and pin9 for - to test backlight current draw? I saw a YouTube where tech disconnected main board cable and backlights came on.mine didnt.any thoughts? Or service info? Thanks,RonL