Shorted mobo?

[Saffe]

So I was being a negligent idiot and accidentally put a USB-C dongle into one of the motherboard USB-A slots, which led to the PC immediately shutting off and now displaying 0 signs of life when I try to start it back up. The dongle also seems to have kicked the bucket, so it looks like a clear case of shorting to me.

 

How likely is it that it's just the mobo and PSU that are busted and that rest of the components are ok? Or ya'll think total system annihilation is the more likely diagnosis?

[mariushm]

Disconnect power supply for a minute or so (unplug the power cable). Some protections / fuses reset once the power is completely disconnected for a bit of time.

[Saffe]

Already did that and still nothing sadly

[mariushm]

USB works with 5v ... My next step would be to see if the power supply is still working. It's possible the 5v output of the power supply has failed and it keeps the power supply from starting.

 

Try disconnecting the power supply completely from components (disconnect 24 pin atx connector, disconnect cpu cables, disconnect everything).  Then try to start it manually by shorting PS-ON pin to any ground pins in the 24 pin connectors. 

 

The PS-ON pin is the 4th hole from the left, if you're looking at the connector with the retainer clip on the top.  Ground is any hole labeled COM in the picture, right under the retaining clip there should be ground wires.  So you can try to start the power supply by using a metal paper click or a piece of uninsulated wire to create a connection between PS-ON and any ground wire. If the power supply can start, you should see the fan spinning (unless your power supply is one of those that doesn't spin the fan unless you exceed some amount of power consumption)

 

If you have a digital multimeter, with the power supply only plugged in the mains, you should measure 5v on 5v stand-by wire which is the purple pin in the picture below. So with a meter on dc voltage, a probe on 5v SB and the black probe on any COM holes, you should measure 5v. When you create a short with a metal paper clip or some wire between PS_ON and ground, the psu will create the other voltages (3.3v , 5v , 12v and -12v) and make them available so you could use a multimeter to check if they work.

If the power supply failed, it would not start up

 

If the power supply seems to work, then most likely there's something still broken on the motherboard that would prevent the power supply from starting (maybe it sees a short circuit and refuses to give 5v so you won't get fires on the motherboard where that short circuit is).

 

I would also actually look with my eyes in the usb type a connector, just to make sure there's no two pins touching each other, maybe being accidentally shorted or fused together. If there's a short, the power supply would detect it and refuse to start. 

Some USB connectors are also powered by 5v stand-by when the PC is off, because it's the only way for BIOS to power a keyboard or mouse while pc is shut down, and sometimes it's useful to start pc on keyboard press or mouse clicks. If the usb connector is faulty it could overload or short circuit that 5v stand-by output of the power supply and also prevent the chipset (and therefore bios) from working.

 

[Saffe]

Thank you so much for the comprehensive answer!

 

However, since I'm a super layman I'll probably just end up taking it to a professional.

I mean, if I can't be trusted to put a USB-C device into the correct USB port, I probaly can't be trusted to jump start a dead PSU lmao.