Has anyone else experienced a MacBook Pro 16, 2019 working then the next day its completely dead?

<< The only next option was to ship it out and only mentioned an initial cost of $685 with no specifics >>

Generally when the send it to a depot for repair, that IS a fixed price, and the diagnosis does not matter, they will "make it right" for the agreed upon price.

"....with no specifics on what hardware or issues needed to be resolved."

That's pretty typical. Apple doesn't actually do repairs, they replace parts and the logic board is a "part". No real need to make any specific diagnoses when 99.99% of the time the logic board replacements fixes it.

It really depends on what the problem is. I don't have a 16" but my wife does and luckily it still works.

But I can think of a few things that could be it that I've seen myself. I've had my Mac just go kaput once and I realized that it was just the system going crazy where it wouldn't turn on or off and there was a light buzzing sound coming from the logic board. I've read about this and the only solution for that is to completely remove the power from the logic board. Some people have just waited for the battery to die, but that can days to weeks and isn't great for the battery. Another is just to disconnect the battery connector, although that's not something Apple considers do-it-yourself.

Another was a time that my battery completely died and it refused to power on even with external power. I'd heard of a special low power mode (and even tried it with an old polycarbonate MacBook) but that didn't work. But the battery came to life during my appointment at the Apple Store while I was waiting for the advisor, and they did end up replacing the battery since it was at about 74% battery health.

Update back in Nov 22. Overnight update and the next morning the laptop worked fine, but the battery was losing power despite the Apple charger being on.

At 10% I phoned apple to ask advice. SMC resets and config print out told them nothing, eventually, 15 minutes later the laptop went off, black screen, nothing I could do.

Under instruction I took it to The Apple Tech Bar who couldn't revive it. I left it for 2 hours and when I returned, still black. I held the power button for more than 10 seconds quite a few times. An apple logo appeared, I logged in and the machine started working again.

No result from Apple. No expense to me. No good either as the same power issue happened Aug 23, deleted in front of my eyes. I left it for over three hours plugged in. Power button for over 10 seconds quite a few times. its now back on.

I9 processor, 2.4Ghz 64GbRAM late 2019 model. (last of the Intel so I could use Windows on a different log in). 4Tb of SSD so no issues with storage. No extraordinary software. Low power mode all the time as the FANS are so noisy when I use one or more screens etc.

By the way, this time when the power depleted, I had three devices plugged in for music updating. Was that too much for this overpriced machine? (I miss my 2015 I7 2.1Ghz 32Gb machine)

Why did you leave the Genius Bar without an estimate?

we can't tell you, but they can.

Yep. Happened with my 2016 MBP. $592US to replace the logic board a couple of years ago.

All things break and wear out eventually.