She claimed her dismissal was unjustified.
The nurse had a rocky relationship with her employer and was investigated for two disciplinary and two performance concerns.
She was earlier investigated for "discrimination" for delaying to give one resident a cup of tea and alleged denying another resident a slice of bread.
Her employer also investigated an allegation that when drying a residents back after showering she "put her finger in a towel and inserted it in her 'back passage'."
She was also accused of poor time management but denied all allegations and concerns voiced by Bupa. She was given a verbal warning, and later placed on a performance improvement plan.
In February 2014 the nurse was given a first written warning due to "failure to meet her performance improvement plan".
She told the authority she was not happy with the company's treatment of her during that period.
In May 2014, a second resident complained to a caregiver that she did not want the nurse to shower her. The resident later told the caregiver that the nurse had behaved inappropriately when showering her.
The nurse's manager later called her to discuss possible suspension and then issued a letter confirming suspension.
Bupa issued her with three letters, the first confirmed her suspension in response to the allegations made by the two residents, the second invited her to attend a disciplinary meeting to discuss performance issues and the third sought to set out the allegations made and possible breaches of her employment agreement and Bupa's code of conduct.
The rest home conducted interviews with the residents who said the nurse had "put a finger in her bottom" while drying her and "put a finger in her back passage".
The nurse was issued a letter that Bupa would report the situation to the New Zealand Nursing Council.
The New Zealand Nurses Organisation lodged a case for personal grievance on the nurse's behalf for unjustified dismissal.
Bupa informed the police about the allegations. The police launched an investigation. However, after preliminary inquiries it was discontinued and no action was taken against the nurse.
The authority said that on the face of it, Bupa's investigation appeared "coherent and robust".
"However, when examined more closely there were several procedural problems with Bupa's investigation, which called into question its integrity and the likelihood of a lack of fairness being afforded to [the nurse].
"A fair and reasonable of employer, given the uncertainty as to how the complaints arose and, indeed, what they even were, would have sought to clearly establish what the allegations actually were before putting them to [the nurse]"
A Bupa spokeswoman said the company was disappointed with outcome of the case but would not be appealing the decision.
"We're a proud employer of over 4,000 people in New Zealand and our people are central to everything we do. We'll take learnings from this case to improve our practices and to reflect the culture we aim for," the spokeswoman said.
The nurse told the ERA she was very upset and distressed by the whole ordeal and was awarded $10,000 in compensation.
