The electric battery ignited and burst into flames, despite not being connected to a charger, he said.
The start of the fire, which took hold in the far left rear section of the 700sq m building, was captured on internal CCTV footage.
Related: Faulty battery caused $2m blaze + CCTV video
Owner Richard Ive said reopening the store would be like "going back home".
It will reopen officially on March 7.
The blaze cost his business upwards of $1.8 million, he said. While he had business insurance, it only covered him for a year.
He would suggest other business owners in Tauranga extend the normal coverage period to 18 months to two years on the off-chance something halted their business operations.
"It's very tough getting things done in Tauranga in a year."