Foxconn confirmed it had sent the messages, saying that under Chinese law the worker must submit himself to a disability assessment—a process that in Zhang's case would require him to be discharged from the Shenzhen hospital and travel 70 km (43 miles) to Huizhou, where he was first hired by Foxconn.
The firm said in response to emailed questions that it would be prepared to return Zhang to the Shenzhen hospital after the assessment, though his father said Zhang was unfit to travel and that doctors felt he remained at risk of a brain haemorrhage.
The case has raised fresh questions over the labor record of Foxconn, one of the biggest and most high-profile private employers in China, after a series of well-publicized suicides among its army of around a million workers and recent outbursts of labor unrest.
It has angered labor activists who say Zhang's plight also highlights China's patchy and sometimes precarious welfare system for workers seriously injured in industrial accidents—and point out that there are many workers worse off than Zhang.
"They kept sending me SMSs every day to get my son out of hospital and to appear before an injury assessment body or they will stop paying all expenses, including his medical fees and our living expenses, " said Zhang's father, Zhang Guangde.
"You cannot imagine the suffering they put me through, how I had to fight every inch of the way just to get money so we can take care of our son, " he added, speaking at his son's bedside at the Number 2 People's Hospital in Shenzhen.
Zhang was repairing a spotlight on an external wall at a Foxconn factory in Shenzhen, bordering Hong Kong, when he received an electric shock and fell four meters (12 feet) to the ground. He has since undergone five operations, has lost his memory, is incontinent and requires careful, regular monitoring.
'Robbed of Dignity'
Workers who are disabled in workplace accidents and covered by insurance are eligible for compensation payouts, once their disability is assessed and graded by a panel of medical experts. The assessment is done after medical treatment is finished.
Foxconn sent the text messages, and according to Zhang's father at one point briefly halted payments to the family, despite a provincial law stipulating that injured workers can remain in treatment for up to two years before they must be assessed for disability compensation.
The company, however, denied that it delayed or stopped payments, saying it paid them on time.
Zhang, whose case was alerted to Reuters by labor activists, has been in hospital since October 2011.
Doctors at the Number 2 People's Hospital declined to comment for this article, but Zhang's father, 50, said they had not indicated that he could be discharged and had said they needed to keep his son under observation after implanting a tube in his body to drain fluid from his brain cavity to his bladder.
"The doctor told me they needed to monitor his condition and that for such serious injuries, a person was allowed to be treated in hospital for up to two years. After that, assessors can order treatment to be prolonged, " the father said.
Labor activists in China say Zhang is just one of many thousands of Chinese workers who are left permanently disabled or chronically ill by workplace accidents, at the mercy of a system that often requires them and their families to fight degrading battles for treatment funding and compensation.
"China now has laws specifying the types of compensation that are due to workers. But in many serious industrial accidents, companies still put workers or their families through a lot of suffering just to get what is due to them, " said Choi Suet-wah of the Chinese Working Women Network in Hong Kong.
"They are robbed of their dignity, " said Choi, who has extensive experience working with migrant workers in China.
Zhang is actually one of the lucky ones, social workers say, pointing out that Foxconn has at least been paying his hospital bills and the living expenses of his family, which has moved to Shenzhen from central China to be with him.
They estimate that at least four out of 10 Chinese workers are not covered by any kind of insurance and are left to fend for themselves when seriously injured in the workplace - despite laws requiring all employers to insure their workers.
"This is just one of many, many industrial accidents in China. And you almost certainly never get what you are entitled to, especially in serious cases, " Choi said.
Foxconn says it is insured against workplace accidents, which means its insurer would meet the cost of a compensation payment once Zhang's disability is finally assessed.
But compensation in China can vary depending on the city in which a worker's disability is assessed—and this, according to Zhang's family, is why Foxconn wants him to travel to Huizhou and refuses to have him assessed in Shenzhen.
Labor activists say wages and compensation levels are all substantially lower in Huizhou than in Shenzhen, one of the most expensive cities in China.
When asked why Zhang could not be assessed in Shenzhen, Foxconn said the law required him to go to Huizhou because he had signed his employment contract there. It added that it was prepared to send him back to the hospital in Shenzhen if the assessors determined that he required more medical attention.
In hospital, Zhang walks unsteadily, holding on to the bed frames of other patients in his shared room and, with a smile, sits down next to his father whose face tightens with emotion.
"He calls me 'mother' and calls my wife 'father'. He can only mimic words you ask him to say, it is meaningless, " the elder Zhang said later, holding a jar containing large fragments of his son's cranium. Doctors replaced a portion of Zhang's skull with synthetic bone.
He said that despite Foxconn's funding—a monthly allowance of 11, 000 yuan ($1, 800) plus treatment costs—the family had racked up 200, 000 yuan ($31, 800) in debt to pay for medicines not provided by the hospital and other expenses.
Back home in central Henan province, the family was building a house for Zhang to live in after his impending marriage when he was injured.
"We were building a three-storey house, " the elder Zhang said. "The project has since been abandoned and all the building materials we bought have been washed away by rain. But these workers still have to be paid. My whole life is over."