Hi Kaine!
Ah you mean the D-pad!
For this you do need to open up the console, but it's really easy to do!
You might want to replace the rubber and clean it there. You do NOT need to remove the motherboard, only the power board to access the d-pad button and rubber.
Clean the power board carefully (and the d-pad conductive buttons on there). And the d-pad plastic button as well. Replace the rubber for a new one and it should be good to go!
Guide: [guide|3269]
Part: https://www.ebay.com/itm/354393945198
With this guide, you can determine if you want to do it by yourself or let someone else do it for you.
If one of the conductive pads failed, damaged and could not be cleaned anymore, I advise to fully replace the power board. Easier then soldering the conductive pads off. That part can be found here: https://www.ebay.com/itm/354118222468?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D277940%2C276806%2C278303%2C277737%26meid%3D0974a028b96c4cd19f1f2972fa780971%26pid%3D101875%26rk%3D3%26rkt%3D4%26sd%3D354393945198%26itm%3D354118222468%26pmt%3D1%26noa%3D0%26pg%3D2332490%26algv%3DSimVIDwebV3WithCPCExpansionEmbeddingSearchQueryRecallAuctionPushoutVectorPrime%26brand%3DNintendo&_trksid=p2332490.c101875.m1851&itmprp=cksum%3A3541182224680974a028b96c4cd19f1f2972fa780971%7Cenc%3AAQAJAAABQEaV4I9HJKT%252BAma5y%252F48RheNQOwjjhNx1TBBgHhk8esWs5z3zJx975POdrziWUU95aCb%252BcH%252Fo7l4U0%252FPi77H1Rdch6GmwDDSpDmtxcJgeZKe92RgqlwX4c6GpwrabeTANV2zLs1napONYobMJ4fRIysGMM%252BdtHXsxCNnBeneo00GXNYOKCQJqp24084xSXwWR1IyuapfPJSL%252FVox21WKYkHDtdVa0jm7Myl8FFzdrUlJg84End3lCK9UtjNKUg2stb0OF28JsyYJt8DypLUmq533SJQWhcHX2IOdXVVEJZEFVvDbMU7EdRdP3maXVFSCGxbegTkVM%252B4UZtlAPzymJTqs7hueJwyubL%252BKMQqRIhS3FoptgKDxD55P8qGN3bsvySDysJVP2gial48o6m8rUT3XPCDJQOEBz3O1iLMno6k%252B%7Campid%3APL_CLK%7Cclp%3A2332490&itmmeta=01JFEZ3J03DW15B7PAH6JKHA45
But try cleaning first! Most of the times this will fix it.