Name, date of death, place of burial, from Find a Grave website found in May 2025:
https://www.findagrave.com/memorial/274226025/william-bartlett
Name: William Bartlett
Birth: unknown
Death: 13 May 1875
Burial: St. Peter's Anglican Cemetery, Ōnehunga, Auckland Council, Auckland, New Zealand
Plot: 106

Also, place of death, date of burial, from Find a Grave website found in May 2025
Son of George and Frances Bartlett
Church Records Baptism Register: born 29 March 1857; baptised 17 May 1857.
Auckland Star, 14 May 1875: Bartlett: On May 13, at Onehunga, Mr William Bartlett, second son of Mr Bartlett; aged 19 years. The funeral will leave at 4pm tomorrow.
Credit for Source: https://www.graveinsightsonehunga.nz
Gravesite Details
Buried 15th May 1875; Age 19

Date of birth confirmed, place of birth of “Onehunga, Auckland, New Zealand”, date of death and place of death confirmed, from a PDF found in May 2025:
https://www.thebestlittlebookstore.nz/excerpts/bartlettexcerpt.pdf