any way to diagnose a dead motherboard?

just received a phone lot that included a korean Galaxy S7 Edge model (aka the SM-G935L). it doesn't indicate any signs of live at all.
upon further google searching, i've discovered an xda forum post that mentioned almost the same problem, saying that the power IC might be faulty. but even a faulty chip must produce some heat, while my mobo has no heat on its chips at all.

any ideas on what chip is broken? should i replace the whole mobo (which i don't wanna do, since finding the exact model here is a bit hard) or is it possible to replace the faulty chip (if there is one)?