Samsung ps42b451 clicking psu

[Liam]

Hi guys

Plasma TV - ps42b451
Psu - bn44-00273d

Just received this plasma TV this morning. I've worked in a few of these before, the fault is that it's not powering up. Clicks 5 times then stops, all caps seem ok, fets 801 and 802 seem ok.

Does exactly the same with y-sus and z-sus disconnected.

Cn801 connection to main board-
Ps_on is at 3.3v
Std5v is at 5.2v
No other voltages because psu won't power on.

Cn802 connection to logic board -
Vs_on at 0v jumping to 3.3 whilst trying to turn on (clicking)
Ps_on also at 0v jumping to 3.3 whilst trying to turn on (clicking)
Gnd
Gnd
D5.3v is at 5.2
D5.3v is at 5.2

No visible cracks on solder anywhere

I need to figure out if psu is at fault or the main board is stopping this from powering on.

Any help guys??