First of all, what is all that crud on the bottom of the board (top, center)? Take a toothbrush with some alcohol and clean that area thoroughly. Take a magnifying glass and a strong light and inspect all the traces and solder joints in that area after cleaning.
With the power supply disconnected and off, I would take an ohmmeter and start looking for shorted components. Usually, electrolytic capacitors on the secondary side are the prime suspects, but check all the diodes and transistors. Note that some parts may be across transformer windings and may indicate a short even though they are OK. If in question, lift a lead of the suspect component and check again.
There are hundreds of online "repair guides" for switch mode power supplies. I like this one:
https://www.repairfaq.org/sam/smpsfaq.htmFinally, I always cringe when a self-proclaimed novice attempts a SMPS repair. Poking around with a supply that is powered up can KILL you. If you are unsure of exactly what you are doing, STOP.