United hope to sign the striker in the next 24 hours, but Warnock revealed the deal is far from done yet.
Warnock said: "Billy is back with us and I'll talk to him.
"I'm not keen on loaning him out, we agreed a good price, if we hadn't he wouldn't have gone anywhere.
"I've not spoken to Billy since Wednesday, we'll sit down and have a chat about his discussions at Scunthorpe."