So the last fw flashed to it was the dezl 580 cure and it now has HWID of 2826. With cure fw loaded it should have Mass Storage Mode enabled but be stuck on the Garmin splash screen, it that what you're seeing?

It would also have the dezl bootloader in region 5 and it's x-loader in region 43 if it's completed a boot cycle or even partially booted after the dezl's ramloader was flashed to region 12.

This is entirely at your risk to attempt: I would flash the DS fw back to it via its individual BIN files on SD... but initially using the dezl ramloader (as Ldr.bin, first overwritten to HWID 2267). i.e. Garmin\Updater\2826\update.txt. If you aren't sure what to do and want me to make a flash kit let me know. Provided you then have HWID 2267 and a working DS you can flash full original DS fw to it so it has correct regions 5 & 43.

You should clear nonvol after each successful flash. This device will have had some potentially damaging/confused data in region 154 after the constant flashing/re-flashing it's experienced and it may even unexpectedly hard-brick. Region 5 is a particularly risky region, if it gets corrupt the device will die and never boot again.

PS: Where did you source V4.00 dezl 580 firmware? Is it really V3.90 renamed?