One last rather dangerous way...
Grip the twig with thumb and index finger and VERY gently, try to twist around.
A 'very' loose feeling usually means a dead/rotten twig.
A 'harder' feel may mean (whala) roots; CAUTION very new/young/fragile
roots may be very hard to detect ( and easy to destroy) - hence my caution...
Apart from the well said above posts, do not give-up on any fig rootings.
Case in point; I had a recent (immature) Tiny Celeste twig that seemed dead.
While throwing it out, I noticed that the lower 2 buds /wood was still viable (green),
SO I stuck it back. 2 months later, wala , a very healthy/vigorous shoot sprouted
from below the soil - go,go FIGS...