I candle and if there's any question, I incubate. They really have very very tiny little brains. OMG if I had an exploding chicken I think I'd die of gag.
If a hen stays broody too long I usually wait the right number of days and stuff chicks under them and take the eggs. Too long and a hen can literally weaken and die. I have a turkey running around with three chicks now - thinks they're hers. Note, not poults. I stole the eggs she kept messing up, substituted chicken eggs and when they should have been due shoved chicks under her from
TSC. I hatched the nearly ruined hatch as best I could and managed 7 out of 11 despite their horrid condition.
Hopefully when she goes to do it a second time she'll have it better figured out, she did hatch 1, chick from the clutch of eggs I gave her. I knew because I bought red chicks and the hatched one was black, hatched the same night I added the red ones - kind of neat timing on my part.
Now as a new momma turkey she squashed two, and lost one to a fight with my partridge rock roo, and another letting them get too close to the dog yard (why I bought six) so losses happen but she has it figured out, she's death on anything near her babies and keeps them clear of the dog area. I'd rather she learned on mutt and hatchery chicks than on my precious poults.
Next time she does it, she'll know which end is up. Turkeys are harder than chickens. I've had chickens lose chicks, mess up hatches etc. Substituting under a hen has a better success rate but no guarantees.
Just don't let a broody go on too long, losing a broody is always tragic.