What happened to lenovo g505 laptop?

Question

Iron

The problem started with the fact that at first 2 left usb ports (which are integrated on the motherboard) failed on a lenovo g505 laptop (that is, they refused in the sense that, for example, you can charge the phone - there is power, but the phone itself
or the USB flash drive is not detected) . Then, after some time, the sound disappeared completely (I tried to reinstall the driver - it's useless, it gives an error that such equipment does not exist, although the device manager showed that everything is in order), finally the third USb port on the right fails. And as a result, the OS stops loading, or rather, it doesn’t even reach the loading of the BIOS, just a black screen and nothing more, although the cooler on the processor makes noise and the DVD drive blinks.
Someone faced such a problem? Bios crashed? Or what else is broken?
PS. I will certainly contact the SC, just at the moment I want to understand for myself what the problem could be and that someone has already encountered such a problem and will tell
you Thank you

Answer 1

Looks like a dead southbridge.

Answer 2

Bridge.

Answer 3

starts to die percent. in this model there is an apu (north percent and video in 1 chip) replacement is about 4-6k, depending on the greed of the service