Method 1, using an .EXE file:

Most HTC devices will have an executable RUU file which will do all the flashing work for you. If not then you need to use method 2.

1. Go to http://shipped-roms.com/index.php?category=android and select your device.

2. Download the file which is relevant to your device, ie; if you want to stock Gingerbread on the Nexus one then you would pick -

PASSIMG_Passion_Google_WWE_3.10.1700.1_GRJ22_release_signed.zip
(Note this isn't an .EXE file but as the Nexus One doesn't make use of them, pay attention only to the file name.)

WWE - World Wide English, this tells us it is meant for devices all over the world and is a generic update.

3.10.1700.1 - This is the radio version,

GRJ22 - This build is the build ID, GRJ tells us it's Gingerbread.

3. Once the file has finished downloading, connect your device via USB and double-click on the .EXE file you downloaded.

4. The program will check your device's compatibility and if all is well, it will start the update procedure.

NOTE: If you are using a stock ROM and you are using the RUU to downgrade, you will first need to create a goldcard.

Method 2, using a .ZIP or .IMG file:

1. Go to http://shipped-roms.com/index.php?category=android and select your device.

2. Download the file which is relevant to your device, ie; if you want to stock Gingerbread on the Nexus one then you would pick -

PASSIMG_Passion_Google_WWE_3.10.1700.1_GRJ22_release_signed.zip

WWE - World Wide English, this tells us it is meant for devices all over the world and is a generic update.

3.10.1700.1 - This is the radio version,

GRJ22 - This build is the build ID, GRJ tells us it's Gingerbread.

3. Copy the file to the root of your sd card (IMPORTANT!)

4. Reboot into the bootloader using the button combo for your device or using ADB type, "adb reboot bootloader"

5. Wait a few seconds for the device to detect the update file.