[Upgrading, Modifying and Unlocking] ergosteur:
I got that too the first time. Try running chmod 0644 /etc/motorola/bp_nvm_default/* after copying the files

http://www.mediafire.com/file/6na86lvb4psqynd/T-Mobile_MB502_02.60.5_1FF_01.sbf

To clarify: here are the exact steps I followed:

I assume you have the Android SDK on your computer and adb set up properly.

These steps performed on a Windows 7 Ultimate x64 desktop, but should work with any other OS.

Flash T-Mobile SBF

Follow Motoblur wizard. Connect to Wifi and sign in to motoblur account

Open Settings, go to Applications > Development and enable USB debugging.

From the notifications pulldown, select USB Connection and choose "Memory Card Access"

Extract the bp-nvm-default.zip onto your sd card somewhere.

Copy http://www.mediafire.com/?yt284q7veceietn (Universal Androot) to sdcard.

From the notifications pulldown, select USB Connection and choose "Charge only"

Open the File manager that comes with the phone, find the UniversalAndroot-1.6.2-beta5.apk and install it.

Run Universal Androot, hit Go Root. Phone will display Woot! Your device is rooted!

Close Universal Androot.

On your computer, open a Terminal or Command prompt.

type adb devices to make sure your device is detected

C:\>adb devices

List of devices attached

022222202000C device

Then run an adb shell:

C:\>adb shell

$

at the $ prompt, type su. At this point a window will pop up on your device asking you to allow "Unknown" root privileges.

If this is successful, the $ will change to #

C:\>adb shell

$ su

su

#

Now, remount your /system in read write

# mount -o remount,rw /dev/block/mtdblock7 /system

mount -o remount,rw /dev/block/mtdblock7 /system

#

Change to the bp_nvm_default folder

# cd /etc/motorola/bp_nvm_default

cd /etc/motorola/bp_nvm_default

# ls -l

ls -l

-rw-r--r-- root root 4908 2010-07-23 21:54 File_Audio2_AMR_WB

-rw-r--r-- root root 2906 2010-07-23 21:54 File_Audio3

-rw-r--r-- root root 3903 2010-07-23 21:54 File_UMA

-rw-r--r-- root root 4930 2010-07-23 21:54 File_Audio6

-rw-r--r-- root root 2578 2010-07-23 21:54 File_Audio7

-rw-r--r-- root root 4909 2010-07-23 21:54 File_Audio2

-rw-r--r-- root root 2390 2010-07-23 21:54 File_Audio5

-rw-r--r-- root root 3255 2010-07-23 21:54 File_Audio

-rw-r--r-- root root 2578 2010-07-23 21:54 File_Audio5_AMR_WB

-rw-r--r-- root root 625 2010-07-23 21:54 File_GPRS

-rw-r--r-- root root 1562 2010-07-23 21:54 File_GSM

-rw-r--r-- root root 2839 2010-07-23 21:54 File_Audio8

-rw-r--r-- root root 3627 2010-07-23 21:54 File_Seem_Flex_Tables

-rw-r--r-- root root 4018 2010-07-23 21:54 File_Logger

-rw-r--r-- root root 2390 2010-07-23 21:54 File_Audio4

-rw-r--r-- root root 56 2010-07-23 21:54 generic_pds_init

-rw-r--r-- root root 4930 2010-07-23 21:54 File_Audio4_AMR_WB

-rw-r--r-- root root 2906 2010-07-23 21:54 File_Audio3_AMR_WB

-rw-r--r-- root root 3254 2010-07-23 21:54 File_Audio1_AMR_WB

#

Copy all files from the extracted zip to the current folder

# cp /sdcard/extracted/bp-nvm-default/* .

Verify that the files were all copied by checking the date:

# ls -l

ls -l

-rw-r--r-- root root 4908 2011-03-11 18:11 File_Audio2_AMR_WB

-rw-r--r-- root root 2906 2011-03-11 18:11 File_Audio3

-rw-r--r-- root root 3903 2011-03-11 18:11 File_UMA

-rw-r--r-- root root 4930 2011-03-11 18:11 File_Audio6

-rw-r--r-- root root 2578 2011-03-11 18:11 File_Audio7

-rw-r--r-- root root 4909 2011-03-11 18:11 File_Audio2

-rw-r--r-- root root 2390 2011-03-11 18:11 File_Audio5

-rw-r--r-- root root 3255 2011-03-11 18:11 File_Audio

-rw-r--r-- root root 2578 2011-03-11 18:11 File_Audio5_AMR_WB

-rw-r--r-- root root 625 2011-03-11 18:11 File_GPRS

-rw-r--r-- root root 1562 2011-03-11 18:11 File_GSM

-rw-r--r-- root root 2839 2011-03-11 18:11 File_Audio8

-rw-r--r-- root root 3627 2011-03-11 18:11 File_Seem_Flex_Tables

-rw-r--r-- root root 4018 2011-03-11 18:11 File_Logger

-rw-r--r-- root root 2390 2011-03-11 18:11 File_Audio4

-rw-r--r-- root root 56 2011-03-11 18:11 generic_pds_init

-rw-r--r-- root root 4930 2011-03-11 18:11 File_Audio4_AMR_WB

-rw-r--r-- root root 2906 2011-03-11 18:11 File_Audio3_AMR_WB

-rw-r--r-- root root 3254 2011-03-11 18:11 File_Audio1_AMR_WB

#

Fix the permissions on the files, even though they look fine:

# chmod 0644 *

Now exit the shell and reboot to recovery:

# exit

exit

$ exit

exit

C:\>adb reboot recovery

Now the phone should show an android and a warning alert symbol.

Quickly press the power button. Some blue text should appear.

Use the arrow keys to move down to "wipe data/factory reset" and press Enter.

Choose "Yes -- delete all user data"

Now pick "reboot system now"

Hopefully now you'll see the pink square with the words "stick together"!

If so, you're almost done!

All you have to do is complete the annoying MotoBLUR setup again, then configure your APN.

TELUS: http://www.telusmobility.com/en/ON/phones_and_devices/setupdata.shtml

Bell: http://support.bell.ca/en-on/Mobili..._Nexus_One_for_the_Bell_Mobility_HSPA_network