Content warning: contains descriptions of torture.
The 48-year-old ex-British Army soldier survived on rations of dirty water and stale bread.
He was also forced to endure marathon sessions of ABBA's 'Mamma Mia' on repeat for 24 hours at a time.
He now has a new layer of hatred for the Swedish pop group.
Pinner told The Sun he was grateful to be home after living through 'hell on Earth'.
"I thought I was going to die. The past six months have been the worst days of my life," he said. "I never want to hear another ABBA song again. I hated them anyway so it really was torture."
He added: "I just am so lucky to be home."
The Brit fought for Ukraine on behalf of his wife's homeland after Russian President Vladimir Putin sent troops across the border to invade on February 24.
Pinner had been fighting alongside Ukrainians against pro-Russian rebels in the region of Donbas when Putin gave the green light to invade.
Pinner was one of five British prisoners of war who were released last Wednesday (September 21).
He was captured in April during the siege of Mariupol and has now returned to British shores after nearly six months of hell.
He recalled the horrific moment that he had to call his wife Larysa to say his final goodbyes.
"I knew it was bad so I called my wife and I gave her my death message. But she didn’t even cry," he told The Sun.
“She just screamed at me that I was a warrior and that I would survive. Those were the last words I heard from her and they kept me going."
After that, chaos ensued as Russia continued its assault against Mariupol.
"It turned into carnage as the Russians ambushed us with mortar bombs and artillery," he told The Sun. "There were so many bodies, it looked like something out of a zombie apocalypse."
When they eventually surrounded him, Pinner said he was stripped naked and had the 'daylights [beaten] out of me for 20 minutes'.
Last week Pinner thought the end was coming when he was told to pack up his things.
But, instead of an execution, he was part of a prisoner exchange brokered by Roman Abramovich, a Russian oligarch and former owner of Chelsea Football Club.
Featured Image Credit: ITV/ Good Morning Britain/ YouTube. ABBA/YouTube
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