What does the logic board do?

The iPod Classic basically consist of a few parts, each with lots of "bits" in them or on them;

• the case, battery and screen (three "parts");
• the hard drive - a small spinning disc which stores the music (the hard drive is another a "part");
• the logic board, which has the electronic bits needed to make the hard drive turn when required, read the music from the hard drive, turn the "code" of the music into something you can hear, an amplifier to supply the hedphones, charging circuits to decide when the battery is full or empty - and bits to respond to the button pushes you make. (The logic board is another "part")

The charging port (a "bit", with other "bits" on it) - the physical connector you can see, is built into (or "attached to" if you prefer) the logic board. So if the connector is damaged, the repair is to replace the complete logic board, which has the "bits" of the charging port built onto it.

Yes, it is the brains (apart from the hard drive).

pepelepew040 wrote:

Will replacing it render my iPod pretty much new?

No, because the iPod will still have the old battery, which will wear out eventually, and the old hard drive.

Yes changing your logic board will solve it, since it controls all things two your phone, but if in water the circuits might be fried