[G1 Q&A, Help & Troubleshooting] YuYe:
HOW TO: Downgrade ANY G1 (GLOBAL) (CRC1)

I’ve made this guide so No more new questions are being raised for CRC1.

I know I’m Hypocrite because I did it as well.

I’ve gathered all various posts into this guide so it’s in one place. This worked perfect for me I’m running JACxHERO 1.2 at the moment.

I don’t take any Credit nor am I responsible for bricking your G1.​

First you format your SD like so:

Format F: /FS:FAT32 /A:4096

The next step is to get your CID from your SD card.

Go to the market with G1 and download Terminal Emulater.

Open the app and type: cat /sys/class/mmc_host/mmc1/mmc1:*/cid

Here you receive a number like " 0353445355303147800208D254008A6E"

Convert the number like this:

03 53 44 53 55 30 31 47 80 02 08 D2 54 00 8A 6E

6E 8A 00 54 D2 08 02 80 47 31 30 55 53 44 53 03 <-- reverse of the top code

Final: 008A0054D20802804731305553445303 <-- the fisrt 2 (6E) we replace by 00

Now your ready to make the goldcard via the link below.

This number you fill out HERE and wait for the almost instant email.

- download HxD Hex Editor and install

- open program and go to "extra" and then "open disk"

- choose physical disk and then the removable disk. that is the same as your memory card. I've you don`t know with one it is. just remove the card and restart the program and you will see witch one is disappeared.

- uncheck open as readonly !!!!!!!

- go to "extra" again and the open disk image.

- open the goldcard.img witch you have created from Viper BJK website.

- press ok (512 is fine) en then "select all" and "copy"

- go to the removable disk tab and select offset 00000000 till offset 00000170 go to "edit" and then past write.

- save it

- now copy dreaming.nbh to the root off your memorycard.(RC7) <-- RC7 works best for DREA110

- turn of your phone and restart by holding the camera and the power button.

Download the Hard SPL:

SPL

Download the Recovery Image:

RECOVERY

1.	All files must be on the root of your SD card.

2.	Restart your phone. Wait for your phone to start up fully and show the home screen.

3.	After your phone starts up, hit the enter key twice, type "telnetd" and press enter. (Yes, it will start up a contact search, don't worry. Just type it.)

4.	Download an Android "Telnet" application from the Market and connect to localhost.

5.	If you connect successfully, you will have a root prompt "#".

6.	Type the following into Telnet (these commands will give you root access easier in the future):

o	mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system

o	cd sdcard

o	flash_image recovery recovery.img

o	cat recovery.img > /system/recovery.img

What To Do Now That You Have Root​

Now that you have root, you will want to apply "Hard SPL" to your phone. HardSPL is what will allow you to apply flash images from other regions (like UK on US phones, and vice versa), create full backups of your phone, install the latest build from the Android source, and usually resurrect your phone if it is "bricked". You have already downloaded the file to your SD card, so now you can apply it.

1.	Power off your phone.

2.	Start up in recovery mode by holding home and pressing power.

3.	You will now enter recovery mode. You should see an exclamation.

4.	If you do not see a menu on screen, press Alt-L to show the menu.

5.	Press Alt-S to apply the update from the SD card.

6.	After the update is complete, hold Home and press Back to restart.

And now, the last step! You are still running an old version of Android, but you want to upgrade to the latest and greatest update! You can do this, and not lose root by downloading modified versions of the updates.

1.	Download the image.

2.	Rename it to update.zip.

3.	Copy it to your phone's SD card.

4.	Turn your phone off.

5.	Start up in recovery mode by holding Home and pressing Power.

6.	Press alt-W to wipe your device. (You need to do this, or the device may hang at the flashing Android screen)

7.	Press alt-S to apply the update.

Now that you have done this you can Flash ROMS that don't use ext2,3,4.

For the Hero ROMS

"WARNING YOU MUST HAVE CORRECT SPL AND RADIO"​

Requirements:

: some knowledge Root, Creating Partitions, Flashing, correct radio and spl etc...

: Root see how Look up in the Post

: SPL & Radio get it (HERE)

: 3 partitions fat32, ext3 & Linux-swap see how (HERE)

: Cyanogen spiffy Recovery 1.4 Image, get it (HERE)

: G1

: Micro sd

Install Radio FIRST

Download the Radio Update

Rename it to update.zip

Remove your SD Card from your phone and place it in your SD Card Reader

Put the update.zip at the root of your SDcard (root = not in any folder)

Insert your sdcard back into the phone

Turn off your phone (Hold power and press Power Off)

Hold the Home button and then press the power button (Keep holding power)

You will now enter recovery

Open up your keyboard and press Alt-S

Let it finish the update

When done reboot by pressing Home and Back

You should be able to access your Home screen (If its stuck on the Google G1 screen dont panic, just remove your battery for now)

Installing the new SPL

Note: To update you must have a PVT board. To Check go into fastboot (Power and Camera and check) Thanks persiansown

Take your SD Card out again and plug it into the pc

Remove the update.zip that you put in there

Download your current Rom or any other ROM that you want. I suggest CyanogenMod 3.6

Download the SPL Update

Rename the SPL Update to update.zip

Remove your SD Card from your phone and place it in your SD Card Reader

Put the update.zip at the root of your SDcard (root = not in any folder)

Insert your sdcard back into the phone

Turn off your phone (Hold power and press Power Off) or put your battery back in and turn it on

Hold the Home button and then press the power button (Keep holding power)

You will now enter recovery

Open up your keyboard and press Alt-S

Let it finish the update

Now it will reboot on its own back to recovery

Reboot again by pressing Home + Back

Your phone will be stuck on the T-Mobile G1 Screen (Again DONT FREAK)

Remove the battery from your phone

Remove your SD Card and plug it back into your computer

Take the ROM that you downloaded and rename it update.zip

Remove the update.zip that was on your SD Card and put this new one it

Put the battery back into your phone

Enter recovery (Home + Power)

Press Alt+s to update

Let it finish

Press Home + Back to reboot

Thats it! You now have your new SPL and Radio

If your in a boot loop you need to re-format ext3, but how?

"Thru Phone terminal"

: Boot into recovery home+power

: Go to console ALT+X

In Phone Console:"type"

(press enter)

#

# mount -o rw /dev/block/mmcblk0p2 /system/sd

# rm -rf /system/sd/*

# reboot recovery

Download your desired ROM rename as update.zip and your off.

Fist thanks go to Google for their initiative and the Android platform

Thanks to Haykuro

Thanks Drizzy Drake Rogers

Thanks DeToX for the GoldCard idea.

Thanks to Viper BJK for the guide

Thanks moneytoo for a perfect guide

Thanks to Koush for this guide

And Many thanks to everyone I forgot and off course XDA COMMUNITY RULES!!!!!