Mr El Sheikh physically resisted two attempts to move him from Manus to Papua New Guinea's capital, Port Moresby, from where authorities planned to deport him to Lebanon.
The advocate, Marilyn Beech, said during that time, Mr El Sheikh was the victim of several beatings by security forces and suffered injuries to his ribs, kidneys, ankle and neck, resulting in a loss of sensation in his left side.
He was eventually moved to Port Moresby's Bomana prison, from where an attempt to deport him on Wednesday was thwarted by a doctor who found Mr El Sheikh was unfit to fly.
Ms Beech, who communicates with Mr El Sheikh on a daily basis, said she was told that during the second attempt to move him to Port Moresby on 3 April, an Australian man bribed a doctor to allow the 29-year-old onto the plane.
"He struggled violently on that plane. There were at least 12, possibly as many as 17 guards and during his physical resistance a plane window was broken," said Ms Beech.
"Azzam was taken off the plane and beaten up and taken back to Lorengau police station. In his cell there were at least ten men including the Australian who gave the order for Azzam to be roughed up, so he was beaten up again," she said.
"He didn't physically fight anybody on the 11th when they succeeded in taking him from Manus to Port Moresby and he said the reason for that was, he knew he couldn't take another beating."
Ms Beech said several doctors who saw Mr El Sheikh in Bomana prison were denied permission to take him to hospital.
Unable to walk and in the same clothes he had been wearing for almost a month, Mr El Sheikh was finally taken to a Port Moresby medical centre on Wednesday for clearance to board the plane back to Lebanon.
"He was told, 'we'll be taking you to the hospital, then you'll go to the airport. You're being deported today,'" said Ms Beech.
"But when he went to the hospital, the radiologist was concerned by the x-rays of his kidneys ... went outside and spoke to immigration officers and shortly after that Azzam was taken back to Bomana prison, which is where he is now."
Ms Beech said Mr El Sheikh was previously offered $US25,000 to return to Lebanon voluntarily, which he refused.
After four years in Australia's detention centre for refugees and asylum seekers on Manus Island, the Lebanese man preferred prison to repatriation.
A Manus Island detainee known as 'Naji' said Mr El Sheikh feared for his life if sent home.
"He doesn't need any money ... he just asked to get protection. All I can say about Azzam is, he will be in danger if they send him back by force."
Ms Beech said she did not have all the details as to why Mr El Sheikh fled his country of origin.
"From what he has said to me, the situation in many parts of Lebanon is more dangerous now since the Syrian war began," she said.
"Comments that were made to me were things like, in Lebanon political parties can very quickly morph into militias and militias in your local area will demand adherence. If you are not a supporter then you're seen as an enemy."
Many of the over 800 men held at the Manus Island regional processing centre since 2013 have fled from conflict zones.
Most of the men have been found to be refugees, but the PNG and Australian governments have not reached resettlement outcomes for the vast majority of them.
There are around 200 asylum seekers processed on Manus who have been classed as "non-refugees", having had their applications for refugee status rejected.
In the past two months these men have been encouraged to return home by officers from both PNG Immigration and the Australian Border Force agency.
Reports from Manus indicate the men are sometimes offered payments of up to 25-thousand US dollars for "voluntary" repatriation.