The 60-year-old had to undergo surgery after falling from his new electric bicycle and breaking his back, dangerously approaching his spinal cord and being paralyzed.
Weeks later, Simon is on the mend and was pictured being taken to hospital in Los Angeles for a check-up.
A pal told The Sun: “A friend of his joked that the metal that held him together made him the Terminator – which amused Simon.
“He won’t mind if it sticks, but the bottom line is he’s on the mend.
“The experts are happy with how things look and he does physiotherapy at home every day. It looks good. ”
The Supreme X Factor was released from hospital last week and was reportedly “in a good mood” despite the pain he was in.
Simon, who shares his son Eric with his partner Lauren Silverman, had to have a steel rod inserted into his back after breaking it in three places in the accident.
He later joked that he should have read the manual after testing his new bike.
Simon is replaced by former BGT star Ashley Banjo, who found fame on the show with her dance group Diversity, when he returns to screens.
But Simon is reportedly eager to be back on the series and wants to travel to London in October for the live-action final.
The insider added that he was working as quickly as possible to regain his strength, but was always encouraged to rest a little longer.
Simon was also forced to miss the America’s Got Talent Live Finals.
He was replaced by Kelly Clarkson, but fellow judge Howie Mandel is hoping to see him back in his seat before the series ends.
He told E! News: “We didn’t know what to expect. I knew we could expect something spectacular because we have, I believe, the most talented crew in the world, in every department possible.
“We were a little confused because we were worried. We were worried about our friend, and our boss, and our leader, Simon Cowell, who we think is doing spectacularly well given that.
“The last one I heard was that after a six hour operation, and a few merged discs, and the rod put on his back, yesterday he was already standing, he’s already mobile!” So as I have been telling a few other people, I don’t plan to see Simon again until this season is over. ”