Sony GDM-400PS No signal Standby Problem

[Minfo]

Hi, I can't find the fault with this monitor (GDM-400PS). When I connect the VGA cable (I tried 3 different ones and built a custom one according to the manual) an image appears looking for a signal, first BNC and then VGA, and since it doesn't find any, it changes between amber and green led in standby.

I've already disassembled the monitor, I'm measuring and looking for any damaged components but I still haven't found anything.

I appreciate any help.

Greetings.