Hi, I shorted my desktop computer accidentally by messing with the usb port. Now it won't even start at all, even with a different PSU. I took it apart and did some tests, I found out that many capacitors are shorted to ground in a certain region. The yellow square indicates the USB plug from which the short happenned. Is there any way I can salvage the board. Could it be one component that is causing the short?

 

If all those 'shorted' capacitors are on the same power line then any shorted component anywhere on that supply line will make the capacitors measure short in circuit. It can then be difficult to locate the actual shorted component though in your case it is likely to be in the USB related circuits.

 

Finding something shorting the power supply on a board like that can be very difficult because the power is usually distributed by large copper areas instead of "tracks".

Here's a method I've used. It requires care and good bench power supply with adjustable current limit.

Set the bench supply output to no more than half a volt and turn the current limit down to zero.
Connect the bench supply in place of the normal power supply, paying attention to polarity.
Slowly raise the current limit while watching the supply output voltage. Start with no more than about half an amp, but in any case don't let the voltage go over 0.5 V (if your leads to you power supply aren't heavy enough, you may get some drop across them - generally it is better to use heavier leads than it is to turn up the power supply voltage setting to compensate)
Now do a finger dance over the circuit board, feeling for components that are warm. Sometimes a part will get very hot, so be careful. As long as the voltage is kept low, you can increase the current to 2 or 3 amps (not all at once, raise it a bit, feel around, then repeat if necessary), but there is risk of causing more damage. You don't want to cause a circuit board track buried in an inner layer to open.

Tantalum capacitors sometimes fail short-circuit. No other common type is likely to fail short-circuit. None of the caps in your photo look like tantalums. Semiconductors almost always fail short-circuit, at least at first. If sufficient power is available they will sometimes then go open circuit - with a bang and smoke.

The section of circuity in question may actually be powered with a local step-done switch mode converter.