Vizio sv470m won't turn on (only orange light)

[Nerd125]

Had this tv for about 3 or 4 years and it stopped working other day. At first it stopped responding to the remote and next day stopped working from the side power button on the side of the tv. Read somewhere that most times it power supply board so I ordered another power board for it but did not fix the problem. Then ordered the main board and replaced it too. The orange light on front stays on but will not "click" on and change from orange to white.

I have replaced:

1.) power board
2.) main board

If anybody knows what to do to fix this problem please let me know. I would greatly appreciate it! Thanks

[Nerd125]

I noticed the main board that was originally in the tv ends in the suffix "5D". The one that I ordered ends in the suffix "5C". I'm not sure if that could be the problem or not because the serial is identical except for the ending. Does anybody know? Thanks