I’ve been investigating a problem on a 9 year old MacBook Pro – it will not start up, but produces a series ion 3 beeps. This is usually said to be a memory problem. I’m still working on this, but I think it is a problem of the mother board not accessing the memory, rather than the memory itself. If this is the case, it is probably not possible to solve it economically on such an old machine.
I have to say that reliability of my various Mac equipment has not been as good as for my Windows PCs.