Source does not turn on, voltage on the electrolytic capacitor after the primary rectifier bridge is very low voltage does not get to have 40v. Visually I do not see any burned component. I suspect that it is the integrated U1 of 6 smd pins but I can not identify the code.

This image I copied from another forum that is of the same monitor model. Can you get the datasheet for this component?

SG6848,SG5701,SG5848,LD7535,LD7550,OB2262,OB2263 analog

See what output is used