Cisco C3560G-48PS POE Switch boot problem, but seems like HW issue

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Hi,

i got a Cisco C3560G-48PS switch, with HW problems, but i have no idea, how to continue..

It does not boot, no boot log on the console port. All of the LED indicators on the front are on, and are green. (not the port LEDs.. just the status LEDs) The fan works, but on the maximum speed. LAN ports are down.

The 50V, and 12V is OK from the internal power supply. All low voltages are OK. (3.3V, 2.5V, 1.8V...) I measured all of the main board capacitor voltages, and checked for spikes, or noise, but all OK.

Next, i resoldered the RAM chips. (according some youtube videos, it is a common problem.) No success.. After that, i replaced the two RAM chips. Nothing. Does not boot.

on the connector of the mains PS, there are 4 cables, what i can't identify. orange, yellow, violet and pink. I can meassure 2.7V on the yellow cable, but nothing on the another cables. Is it normal? It look's like, this pins are comming from the external PS connector (if someone uses an external common power supply, not the fitted 230V one.. It has a different connector on the back side of the switch.) i think. Is it normal, that no voltage are present on this cables? What is the 2,7V??

I have no other switch like this, so i can't compare it with an other.  But i have a C3750-24PS. With the same fault. (does not boot, all indicators are on, except the port LEDs..) It has got a different power supply, but with the same connector. Same.. no voltage on the same cables..

Does someone have any idea what i can do to repair it? It's a 48 port gigabit switch, with POE on each port.. i don't wan't to throw it away..

Thanks!