The batteries corroded in elmo’s foot can this be repaired?

Pamela Adams you could most likely solder new contacts/springs in its place. Post some images so we can see how bad the damage is and where to attach the new ones. Aggiungere immagini ad una domanda

You could get some wire and solder it onto the spring part. You could even bring some wire from the out side through the case. Of course I would suggest that you replace the spring contacts with something like this

Instead of cleaning it with baking soda use a diluted lemon juice solution to resolve some of the rust and debris from the alkali of the batteries. Once cleaned use a lightly oily rag to wipe down the lemon juice and lubricate the contacts.

Not a real bad repair and not to expensive