[SOLVED] Problem: Shorted MB?

Jul 8, 2020
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My son built his computer with parts he bought from a friend. It's been working great. He wasn't paying attention one day and accidentally plugged his laptop charger into the USB port on his keyboard (yeah... it fits... not well, but it's a square lenovo power supply and the USB port on his keyboard has pins not a plate.. and yeah he can't believe he did it either). The computer was on and the laptop power supply was plugged in. The computer immediately shut down and now won't reboot. Doing what research I can, we've tested the corsair power supply per the corsair website (jumper pins 4&5 and fan spun when powered on). We also tried to reset the CMOS by shorting the CLRTC pins for 10 seconds with the power supply unplugged. Didn't work. When you power on the machine, there is an orange light on the MB labeled SB PWR LED, and some LEDs in the case/MB come on. The CPU fan spins for a second and then powers down. No beeps. No monitor power on. No keyboard light up. Nothing else.

Any ideas on what else we can test or what might be wrong? I haven't built a computer myself since the old 386/486 days, so I know enough to be dangerous and have read a lot of info from helpful people here. Oh and does anyone know where to get rid of old 386/486/early pentium MB/CPUs? I'm moving and it's time to purge my parts bin in the garage :)

MB: ASUS STRIX Z370-H Gaming LGA1151
Video: MSI GTX 1070 8GB
PS: Corsair CX750M
RAM: Corsair Vengence LPX 16 GB (2x8GB) DDR4-3000 CL15
Case: Raidmax Viper II ATX Mid Tower Case
Has a standard HD and a Samsung 970 EVO 250 GB SSD
Intel core i7-8700K 3.7 GHz 6-core processor

We've unplugged all the power cords and replugged them in just to be sure it's not that.

Thanks in advance!
Steve
 
When you power on the machine, there is an orange light on the MB labeled SB PWR LED, and some LEDs in the case/MB come on. The CPU fan spins for a second and then powers down. No beeps. No monitor power on. No keyboard light up. Nothing else.
The SB_POWER_ LED is supposed to stay on. That LED tells you that everything is OK and standby power is available to the board. But considered what happened, maybe you're right about short motherboard.

Try to boot with no one USB port is connected.
Do you have another motherboard to test ?