I disagree. Many do make it. Many live long healthy lives with bent toes as well.
I myself have a 5 year old cross beaked bird that remains healthy despite her deformity.
In my experience raising chicks (never used an incubator all mine were feed store or ordered chicks) that bump may be poop it cannot get rid of either from being weak or from poo build up near the vent.
I would clean that bottom up.
Seeds mean the need for grit. That chick is to weak to eat...
For a chick that age I would offer raw egg yolk.
I am no great expert on this but know those questions are the ones you would surely be asked.
I am sure more help will find your thread shortly.
If you want it moved to the emergency section let me know and I can move it.
Age of chick?
Eating? Drinking? Peeping a lot?
How does its poop look?
Brooder set up? What type of heat source?
What feed are you using now? Age of feed?
Symptoms in detail and a pic of the chick so we can see posture please.