Definitely nothing to do with my computer.

I've tried 4 different laptops with various configurations. It always resuts in Nokia DLoad with the boot to WP7 following.
The people who have this working don't get the WP7 boot after disk mode which suggests that the bootloader of the phone is acting differently.

So it's entirely down to the bootloader the user has and nothing else as far as I can see.
Although, even with the same bootloader version two users are getting different outcomes so perhaps it also depends on the region of the firmware?
I'm out of ideas

By the way:
Diagnostics App Version: 1.9.4.0
Firmware Revision: ...12070 (I updated just now)
Radio HW Revision: 8255
OEM Device Name: RM-801 SE 615
Device HW Revision: 112.1402.2.3

Note: I have one of the first retail units. It was sent to me by Nokia before the public release.

Im not sure if this will help but;

The Nokia 800 uses a NAND lumia eMMC
The capacitive touch digitizer is an ATMEL mXT224
The controller is a Broadcom WiFi BRCM4329

What we currently need is info on how to initialize the screen and power it on from within a custom bootloader. More specifically, we need the right addresses for the screen and the framebuffer. Any developers that have experience in modifying the LK bootloader?

Sent from my Lumia 710 using XDA Windows Phone 7 App

I just realised something. Which hardware Lumia 800 are you guys using? Also, which method did you use to update?

RM-801 (900MHz)
or
RM-819 (850MHz)

AND

Zune update
or
NCC/FiRE update

I have a RM-801 with Zune update and not working.

Originally Posted by xsacha

I just realised something. Which hardware Lumia 800 are you guys using? Also, which method did you use to update?

RM-801 (900MHz)
or
RM-819 (850MHz)

AND

Zune update
or
NCC/FiRE update

I have a RM-801 with Zune update and not working.

I have a RM-801 EU 222, HW revision 112.1402.2.3, updated to 12070 through zune, and it shows up as a removable disk.

RM 801 with HW 112.1402.2.3 and updates via Zune only. Currently this phone is on the 12070 firmware. I sent it to a Care Point once, maybe they did something there....

What's the firmware/region name to get EU-222. I'll try and install it.

some update methods leave bootloader untouched , im still trying to refurbish and flashing different regions on NCS cuz cab method leaves bootloader untouched and zune im not even sure so please send me your phone details and firmware ver and also info like vodafone_es_retail mode v1 black for ex if you know it and got qualcomm mode working on lumia 800
eu 222 is gb

OK guys, I think I found the issue.

If you have *EVER* flashed (without zune) 11501 or 12070, you will not be able to do this.

These two firmwares include a new file (not seen in earlier firmwares) called prod_generic_nokia_osbl.esco. That is the bootloader right?

I flashed 11501 using Nokia Care Suite. Hence, I have the new Nokia DLOAD bootloader.

Note: It's a 935KB file. Someone posted the new 'locked' file vs their dumped 'unlocked' file earlier and showed that unfortunately it requires a signature.

Note: Some RM-819 firmwares didn't include the new bootloader. It's only if you flashed that file!

this is not correct i know a guy who flashed using NCS and then he got it working