If this fails, get a good view of the nasal septum with a speculum and identify the bleeding point. There should be no bleeding at the time of procedure. Apply a topical anaesthetic with cotton wool held in forceps.
Cauterise one side at a time. Apply silver nitrate for about 45 seconds using a fine silver nitrate stick. There will be some whiteness due to vessel spasm and there may be some bleeding in the following few days.