How to identify a broken (? )logic board / power component.

My mid 2014 MBP had possible (??) water damage after a water pipe burst where I'm staying while overseas. There were a few drops of water on the outside of the case, hinge side, but there was no sign of water internally. However it won't power up and the MagSafe DC-in plug (60 watt) has no indicator light when connected and powered up. I took it to the local Apple service centre but all they told me after checking it was that it must be the logic board since it wouldn't turn on but couldn't give me any more details other than that.

Is there a way to tell if it is a faulty logic board or which component on the board is faulty, if in fact it is the board that's US in the first place, or a way of at least ruling out what components aren't at fault? I'm not too keen on automatically replacing the board when I don't have a lot of confidence in the expertise of the local Apple techs, especially when they didn't seem to have any real idea of what the problem was other than the laptop wouldn't turn on.

The battery is the original one that came with the laptop when new. There has been no problem with it up to this point although there is some slight swelling apparent which may be normal for its age. Any advice or suggestions would be appreciated. I'm trying a few of the fixes that have worked for others but no luck so far. Thank you.

Sky P