It has to do with the thought of "the package." There is not much the usual owner can replace but third party repair such as ikenfixit.com, notefix.com can beat the usual repair counter since they might replace the burnt parts rather than the usual entire mainboard.
In closing, the parts sometimes look burnt, sometimes not. So visual inspection of the components (plus a background in inspecting such) may or may not tell us what to replace.
I posted this in computer help also. I used an aftermarket ac adapter with the polarity reversed. Now, with the correct adapter, nothing works. Is there a reset or fuse or something to fix it, or is it fried?