An 11-month-old girl who was rejecting solid food had a button battery lodged in her throat for four months.
Doctors thought Sofia-Grace Hill had tonsillitis or a viral infection until an X-ray revealed the battery the size of a 10p in her oesophagus.
She underwent a two-hour operation to remove it and is now on a liquid only diet.
A surgeon said her survival may be due to the battery being old and without charge.
Dad Calham, from Swindon, first noticed something was wrong in January 2020 and had countless paramedic call-outs and visits to the GP and local hospital.
He was convinced there was something else going on as Sofia-Grace would only eat pureed food.
After another hospital trip in May, she was given an X-ray which showed the battery lodged in her oesophagus was causing serious damage as it had corroded.
Mr Hill said: “I was gutted when I saw it and angry at myself. I blamed myself, but now I realise there was nothing we could have done to know.”
Sofia-Grace had a feeding tube fitted to help her with food and to stop her throat from closing.
Every two weeks she has a general anaesthetic to stretch her oesophagus but faces the prospect of further surgery.
Mr Hill said: “The damage has left a pocket in her oesophagus which needs to close but Sofia is improving week by week with regular dilations which is improving her oesophagus.
“But I know the chance of survival in the first weeks after this happens is very low so we are moving in the right direction.”
Mr Hill is unsure how Sofia-Grace, now almost two-years-old, got hold of the button battery and warned parents about the dangers.
He said: “Just get rid of them or lock them away and don’t give your child car keys to play with. Always trust your instincts as a parent.”
Janet McNally, consultant paediatric surgeon at Bristol Royal Hospital for Children, who is treating Sofia-Grace, said her survival may be because the battery was old and had lost its charge.
She said that without someone seeing a child swallow a battery or obvious symptoms it was not unusual for it to be missed.
“Clinicians and the government have been warning of the dangers of button batteries for a long time. But not all parents are aware of how dangerous they can be.