iMac 21.5 2014 no power

[MDY]

I checked the power and has 11.8V
When I conncet to 230€ first led turn on for 0.5 seg. and then off.
Could be bad power board or motherboard problem? Any test I can do more?
Board is 820-4668

 

[dukefawks]

Probably a short that trips the power supply. Check all rails for shorts.