A very brief summary. Since OS 13.6 (Dec 2023), every time I tried to install new system software, I would get an error called “failed to personalize.” There is a saga of this in the archives.
No amount of work by an authorize apple repair center could resolve it. Finally, after showing up three times over two weeks with the error, I PLEADED with them to physically replace the “mother” board. It took 14 days. I am outside the USA and that added to the delay, the complications, etc.
The board that was replaced holds the internal SSD RAM. The SSD drive was not replaced. OS 15.4.1 came out and I was very very apprehensive to install it. I feared the error would return. Last night, I clicked on the install and went to sleep. This morning, 15.4.1 was installed. Maybe I can declare victory?