Wiring loose.. those light/dimmer wire they give ciplak cable not much thicker than hair one
so it is not uncommon for them to break loose

If I were you I'd buy a dozen of the clamp-type wago connector like these https://my.element14.com/wago/221-412-ve00-...2pos/dp/2536249
make life easy no need to struggle due to the thin wires falling out from screw terminal block