Best not to make major edits to a post once you've received a reply. That would have been better as a new post seeing when i answered it above you'd originally asked only 'Can you please explain how to get the firmware it says to use GarminExpress to do that?
In short, the unit wasn't in pre-boot mode at all going by what you've posted in the edit above.
What do you mean by 'gone thru the whole unbrick process'. You should say what you've done in detail.
e.g.: "1. Flashed cure3 firmware; 2. Reformatted properly with RMPrepUSB; 3. Flashed original fw; 4. It can now enter Mass Storage Mode, GE offers a map update but neither it or WU is offering other files". Is that what you're saying? If not, say EXACTLY what you've done and what was observed at each step or we'll be guessing too much.
If you still can't get past the logo splash screen [is that what you're calling 'the main screen'?] but can now access MSM, that would indicate that you still have the cure fw on board. Cure fw CAN'T boot the unit - that's the whole idea of it so that the boot process bypasses loading maps and other files, one of which is preventing it booting with original fw on board. A still-bricked unit can't access MSM unless it's got cure fw loaded in other words, nor can it be hard reset.
Post again with a 'blow-by-blow' of precisely what's been done and observed.