A torsion spring under tension can put someone in the hospital, and that doesn't change based on how new the house is. If your door won't open and you suspect a spring, that's not a weekend project regardless of build year.
What is reasonable to check yourself on a Newcastle house built in the late 1990s: the photo-eye sensors near the floor, since a knocked-out-of-alignment sensor is a common nuisance call on openers from that era and takes thirty seconds to fix once you know to look. Also worth checking - whether the door is binding on one side, which on a torsion system usually points to a bent track rather than the spring itself, and that's a different repair with a different price.
What we don't recommend doing yourself: adjusting spring tension, replacing cables, or working on anything connected to the torsion bar. If the fix is beyond sensor alignment or a stuck roller, it's worth a call rather than a trip to the hardware store.