Repairing SMPSUs often requires signficant electronics skill. You might get lucky and find just the chopper transistor or line-side DC bus fusible resistor is duff, but sometimes there will be a dozen parts that fail at once, and if you replace only eleven of them and leave one bad one, all the others fail again immediately you power it up. I'm an electronic engineer with experience repairing SMPSUs and I would not tend to bother with one that I can replace off the shelf. Only if it is specialised or unavailable would I get stuck in.
The topside of the PCB has brown glue around various parts. Some versions of this glue turn corrosive over time and attack the parts, leads and tracks.That is enough to dissuade me from getting involved, but if you are curious...
If you have the skills to safely use a multimeter on a circuit that is live with 230V AC mains and 325V DC, power it up and check whether there is 325V DC on the reservoir capacitor. If not, check the NTC and possibly fusible resistor or wire-ended fuse either side of the AC inlet. If either is open, check the chopper transistor and reservoir for shorts. Also check for dry joints on the pins of the AC common-mode choke because there's a suspicious black ring around at least one of them.
If you have line-side DC check whether the chopper is running. If not check the transistor and anything in the primary circuit of the transformer e.g. current sensing resistor plus the efficiency diode(s). Also look for a high value resistor feeding the startup reservoir cap on the line side from the DC bus, that powers the circuit until it's running and can power itself. These often go high / open. If the chopper is running in burst mode or cycle-by cycle limiting, check the output rectifier and smoothing for shorts.
Beyond that you are into needing some proper diagnostic skills and kit.
Beware residual charge on the reservoir after powering up, if the PSU is not running. There are bleeder resistors but if they fail the capacitor can remain charged to a lethal level for hours or days. Always check and discharge if needed before handling.