Memory module crap on MacBook Pro with Retina display

Well, let's get some facts before using up all this blanked out language.

Exactly what model/year is the Mac?

How much RAM is installed?

And, exactly what is that $475 for?

You are stating "memory module" - that would be the RAM modules.

That is important because, after 25 years of working with Macs, I've never heard of a RAM chip being the problem in trying to update the OS.

Or did they say that the hard drive is failing? Which is an entirely different matter. All hard drives fail sooner or later.

And, a side observation: since you started a support ticket before your warranty expired, why didn't you reference that when asking for support/service? High Sierra is now just 3 months or so shy of a year old, so it is getting a bit late to make a claim on that. You should have done that last year. But, since it is too late, let's see if we can work on and figure out the problem.

The issue is that the memory modules are now fused (?) with the computer's RAM

In that model, the RAM chips (there are no modules or sockets) are soldered directly to the mainboard and cannot be replaced separately.

I was told that the only way for me to fix my computer to to send it to their repair depot and "it will be a flatrate repair that will have to be charged..."

The definition of flat rate repair (especially from the depot) or is that they fix everything that is wrong with your computer for that one flat rate. Elapsed time if parts are available runs about a week on average, depending on parts availability.

Check with them again and be sure you understand what they are proposing. Most Apple repairs are deliberately flat-rate, so that any add-ons (like it takes them way longer than expected) are their problem, not yours.

And as babowa said, remind them that you had a repair ticket on this issue before, while it was still in warranty. the worst they can say is, "that does not apply to this problem".

Ok, telling us your model explains the rest of your story. Yes, in some newer models, the RAM is no longer a separate chip, but fused/glued to the logic board which is why it is so expensive. I checked the ifixit.com site for parts and they are offered at $500 and up depending on the exact model with you having to do the teardown and install. So, the price quoted to you is fair - that part includes everything = it IS your computer, so to speak. Unfortunately, it also includes the RAM modules, which are not bulletproof and can fail.

Having said all of that, I've never heard of an OS upgrade which fails because of a failed/bad RAM module, but that is what yours says. I would question the Genius Bar on that. Before making a decision, I would take it back to the Genius Bar and also have them run their diagnostic tests on it - pay attention to the results of the RAM modules, logic board, flash storage, and all the ports. If it all passes, I'd consider running it on the current OS (is that 10.12.6 or ??).

So, I take it that you did not start a support ticket until recently (after your warranty expired)? If you did before it expired, bring that up as well during your visit.