Would WD40 work?
I don't think there's ether in there, so it wouldn't.
I would say no. WD40 is a lubricant. Please - if this is a pet that you love, spend the extra bit and take her to a vet if you can't do it quickly and humanely. In my opinion, suffocating an animal is neither.
Just letting you know that it's the CO2 method (aka baking soda and vinegar) that suffocates birds to death, which is horrible and I don't think anyone should do. Using ether just knocks them out and then kills them in their sleep. They don't know what happened. Vets used to use it as an anesthetic before we developed safer ones that are less prone to overdosing the animal, but in this case, an overdose is what you want.
Not saying not to take the bird to a vet, if they have the money, just that ether doesn't suffocate the birds.