power the board up on the bench
first check the high voltage cap. you should get 300v dc or there abouts. if you have not then check components before this again , resistor, sometimes an inductor etc. if anything blown chang chip as well
then find a low voltage cap and see if you have any voltage. if you have none try changing the power chip. they do fail witthout blowing something
if you get a voltage that comes and goes then another chip on the board has fried. the power chips have “fold back” which means if they detect an over current they shut down and reset
Dave