I was looking this the wrong way, I'm not suposed to have 5V on CN 802 pin2, that only goes high when the inverter is broken.
I noticed I had a pulse voltage on PS_ON. 5V PSU on, 0V PSU off.
I did the following, I removed PS_ON from CN 802, so PSU was always on, but after that I start having problems with the backlight, going on and off and randomly changing brightness.
I know the inverter was working properly, so I removed BLU_ON and E-PWM from CN 802, and left it full on.
I then started measuring the voltages on the output of the PSU.
B5V was not stable, going from ~3 V to ~5V.
B13 was stable at 12.45V and A5V was stable also at 5.12V so it had to be on that part of the circuit.
CB857 was out of spec, I replaced with a 470uf 16V (real 500uf) and that B5V was ok again and PS_ON was stable at 5.21V.
TV turns on again.
I connected E-PWM and left the other 2 out, I'm afraid all this constant on/off will eventually toast the inverter or the mainboard.
I still have random turn off at the PS_ON on the side of the mainboard, TV crashes and comes back up again with the message on screen saying the mainboard is now and I need to go to service mode and configure it again, maybe my problem now is only configuration?