I have two U3818DW Dell monitors, one purchased from Amazon, the other one from someone on Facebook, without an invoice. I'm aware that the warranty might not be available for the second one, but in case something goes wrong (even a firmware update fails), is there a way to get any help from Dell even if I have to pay for it? Sorry, but the idea that even a firmware update can break a $1000 monitor is a bit too much.
On the rear label of each of those is the service tag number and express service code. You should get both of those service tag number transferred into your name. Once in your name, we can then look at the remaining warranty periods. But, until all of that is complete, do NOT install a monitor firmware. Just because a firmware is newer does not mean that you should install it. Firmware M3B103 only fixed a very specific, intermittent, random device detection over USB-C. So if you do not have that issue, do not install M3B103.
Thanks, Chris, I went ahead and transferred both in my name. I already updated the one purchased from Amazon before reading about the firmware update issues but I'm afraid to do it with the one I've purchased from the third party.
Yes, I think it shows the symptoms of the 'random device detection over USB-C'.
When I have a MacBook Pro (turned off) connected over USB-C and I connect another laptop/desktop over HDMI or DP, after about 15-20 seconds the monitor switches the input source automatically to USB-C and shows a "no signal over USB-C" or something similar to that, unless I disconnect the MacBook Pro from the USB-C cable.
You need to test the monitors on a dedicated Windows operating system PC. You can see here on the Drivers page and also in the User's Guide that the Apple proprietary hardware and operating system were never tested/validated by Dell.