2021 M1 iMac (24”, 16GB/1TB) – Persistent horizontal lines, overheating display corner. Flex cable fix?

Hey everyone, I own a 2021 M1 iMac (24-inch, 16 GB RAM, 1 TB SSD). I’ve been using it daily since September 2021 without any issues until December 2024, when I started noticing persistent horizontal lines on the display.

Initially, it looked similar to what others have reported here on Apple’s forums: https://discussions.apple.com/thread/255220596?sortBy=rank Over time, the problem got significantly worse. Almost half of the screen is now covered in horizontal lines.

Since this is my only computer, I had to switch to using an external monitor. The external display works perfectly fine with no artifacts or lines at all, which strongly suggests the issue is with the iMac’s internal display hardware and not the GPU or logic board. More recently, I noticed something even more concerning: the corner/edge (vertex) of the iMac’s display started heating up significantly. It gets so hot that it’s literally not touchable. Because of this, I’ve tried avoiding using the iMac altogether. Apple’s solution is, unsurprisingly, a full display replacement which costs a fortune and honestly isn’t something I can justify for a 4-year-old machine. While researching alternatives, I came across several posts and teardown guides suggesting that the issue could be related to the display flex cable, and that replacing it might mitigate or even fix the problem:

iFixit display replacement guide (shows internal layout and cabling): https://www.ifixit.com/Guide/iMac+M1+24-Inch+Display+Replacement/143953 iFixit community thread discussing horizontal lines on the 24” iMac: https://www.ifixit.com/Answers/View/805617/Horizontal+lines+over+iMac+24+screen

I also found that the flex cables themselves are relatively affordable compared to a full panel replacement: https://www.sparesonly.in/collections/imac-24-a2439-2021

Before I attempt anything risky, I wanted to ask: Has anyone here actually replaced the display flex cable on a 24” M1 iMac and seen real improvement or a permanent fix? Did it reduce the lines, stop the heating, or was it just a temporary workaround? Any insight, personal experience, or warnings would be hugely appreciated. Thanks in advance