Heads up, I have an older iMac that ceased to function after an update. The system told me the graphics card was broken and the Apple staff told me the thing was dead and I needed a new computer.
Turns out, it was a deliberate destruction of the product by Apple. After much mucking around and research, I was able to get the machine to work again. It still doesn’t work as it once did, but at least I can use it for back up and as a spare internet terminal for the wife.
I’m not dissing Apple, I’m just stating the facts. That firm will decide when you need a new product, and they are not shy about leading you along the righteous path.