Headrush Guitar Effects pedal board restarts during bootup

[Yamin]

Hi guys, I've got a guitar effects pedal board in for repair. Basically what happens is when the power switch is pressed, the boot-up sequence starts and then quickly turns off. The switch doesn't turn on the power supply but it turns on the processor(the switch doesn't latch). When the mains is connected to the device there always is standby power.
Anyway first I thought it was something to do with the power supply - it checked out ok. No hiccups whats so ever, However I found out the following - there is a voltage regulator on the main board. I measured the output of the regulator and it measures 12V, but one the power on switch is pressed the voltage goes down until the device turns off and then the voltage at the regulator output climbs back to 12V. I figured there was a short somewhere on the main board, how I came to that conclusion - I removed all the wires going from the main board to other boards and still get the same behavior  when the power switch is pressed.
The model of the pedal board is very new so there are no service manual/schematic. So tracing where the problem could be is very hard. However I came across a potential breakthrough, I noticed some corrosion at the USB chassis pin. I measured resistance between pins and noticed that between D+ and Gnd pin I got a reading of 4.6 ohms. That seems a bit odd, could this be the issue?
Any help on the issue will greatly appreciated.
Thanks in advance.

[joletopo]

Hello Yamin,

Finally did you solve this problem?

Thanks for your support

Regards

[nikifena]

I did it!
I fixed one headrush with the same issue.
The problem was a short inside the processor. Here you can check my video: