I will be happy to assist you with this question.
To reset the tv,you need to press vol minus on the tv set,until volume reaches zero,then,keep vol minus pressed and press "menu" on the remote(while aiming the remote toward the remote sensor).Keep them both pressed until you get the self diagnose screen.
Wait until you see a chart with some parameters checked OK.
Then you need to unplug the unit.
Plug it back,and turn it on.
Now you have the initial(out of the box) screen.Follow the setup,then check the HDMI inputs.
If they still do not work,then you will need to replace the "A board".
I can help you with the part#,but I need the model# ***** this!
I hope this helps,
Thank you ,and have a great day!