SP-FORUMS

TBA possibly next week.
SP-404MKII app, to be installed from Roland Cloud on Mac/Windows.
Introducing: SP-404MKII App
GRAPHICAL EDITOR/LIBRARIAN SOFTWARE FOR THE SP-404MKII
The SP-404MKII is the latest and greatest incarnation in the celebrated Roland SP sampler line, perfect for performance-based ...

OCRed the additional info screen from the Sam Ash listing
ADDITIONAL INFO

• Vivid OLED display for visual waveform editing, full menu access, and more
• 17 velocity-sensitive, RGB pads with no-click design for smooth playability
• Faster workflow with quick startup and load times, 16 GB internal ...

Paging everyone who thinks there isn't SD card functionality.
Found in the Sam Ash additional info screenshot.

The changelog (Google) translated from Japanese is as such

Changes

[Ver.1.05] [Ver.1.04] [Ver.1.02]
[GATE] / [LOOP] / [REVERSE] will be effective for Sample of Protected Bank while Resampling is in standby.
Fixed a bug that does not display an error even if Truncate can not execute due to ...

1.05 is available on the japanese Roland site but for some reason not on the english
https://www.roland.com/jp/support/by_product/sp-404/updates_drivers/

I've converted the .sit archive to a .zip
SP404_105.zip
The CRC32 checksums of the firmware files are
9390f0f0 SP404_105/DCOAPL ...

I don't know why that's happening but I'd try make an image of the drive and restore that image. The idea is you're then doing a bit-level copy which is identical and not a simple file copy.
This won't work when going from a larger drive to a smaller drive as it would truncate off the end of the ...

I think it does a checksum test of factory data Roland would put on the SM card for test mode.
I don't think it's something that's been made available to the public but I may be wrong.

Have you tried another computer, or OS?
Can you format the card on your computer?
It could be a bad card reader.

btw you posted this thread twice http://sp-forums.com/viewtopic.php?f=6&t=24773

Here's a searchable version of the owner's manual unlike the one on the Boss website

Is there anything functionally wrong with your SP?

from service notes
2. SMARTMEDIA & SUM CHECK
Check the writing of the factory-shipped sample and pattern data and
Checksum.
* In this test, pressing the [CANCEL] button retests only the [2.2 SUM CHECK].
It looks like this will fail unless you have the factory data on the SM card.
That's something ...

I don't know, but the SP-404 was made to use cards up to 1GB. I'd try a card that size or smaller.

How can you check what OS you have and what is the difference, surely?
from m

Use the following steps to display the current Operating System Version of your SP-303:
1. While holding down FILTER+DRIVE, PITCH and DELAY power the unit on.
2. The display will show “Ver” and then briefly show the ...

I don't understand what you mean, could you go into some more detail?

Weyes Blood
https://youtu.be/lVfPYvB2osI