Mac Pro turns on no screen no light on keyboard

Hi all

i got issue with Mac Pro 4.1 upgraded to 5.1 , 2 x 3.33ghz 96g ram gtx285

problem is Mac turns on fan spin I can hear hard start spinning, graphic card fans spin But nothing on screen and No light on keyboard

problems started after I tried to clean the keyboard and Mac was off but keyboard was connected to front panel

I changed front panel , I changed power supply

When I press Diag all led on motherboard is green except 5V STBY which is yellow

I don’t know what else to do

I have tried to reset power management on motherboard as I don’t get any light on keyboard

I have done most thing on user manual, again I have changed PSU

I have clean and brushed motherboard to make sure nothing extra on board