The centre-forward hopes to turn things around under new manager Ivan Juric.
Onuachu told the Daily Echo: “It’s been (an) up and down season. First of all, we were talking about transferring and leaving the team.
“It didn’t happen. I kept working hard and believing in myself. Russell Martin saw I had potential and started including me.
“He started to believe in me. He gave me some chances and I think I executed them very well. Now we are here."
He continued: “Russ spoke to me when I got back from loan but I felt like I probably wasn’t going to get a chance like he told me.
“I just wanted to leave (and go) where I could play more. But he actually spoke to me saying he wanted me to stay.
“I felt like, probably, that some minutes is not really being involved. I wanted to leave at that time. This has happened a lot of times already in my career.
"I don’t care if I’m training with the B team, C team or by myself. I give everything when I am training, whether that is with one coach, two coaches or three coaches.”