So the reason why the autofocus would only work while the zoom ring was set to 135mm (when the lens was stuck) has to do with the [[Canon Lens Zoom Brush|zoom brush]]. The zoom brush moves with the zoom ring and tells the lens what position the zoom ring is in. The lens needs this information to properly focus the lens. Since the lens was stuck at 135mm, if you moved the zoom ring to any position other than 135mm, the lens would be trying to focus the lens for the incorrect focal length.
As to why it's no longer focusing at all, there could potentially be a few causes depending on what's going on with your lens. Did you get the issue with the zoom fixed, or is the zoom still non-functional? Also did the autofocus just randomly stop working all together, or if you did repair the zoom issue, did it stop working only after the repair?