[Nexus One General] jmattp:
Most of this information has been repeated so many times. But I wanted to make a short list of all the silly mistakes and simple oversights I’ve made over time.

(I make mistakes constantly - there are probably some mistakes in this very post - and I usually search around and try to find my way out of them. I will edit this post whenever I run into a problem. If anyone has any input, I will gladly add it to this post.)

YOU CAN NOT COME BACK FROM UNLOCKING YOUR BOOTLOADER:

If you ever think you’ll need to or want to “relock” your bootloader, you can’t.

Alternative root method:

VISIONary

(when you launch the application, you can leave everything unchecked)

Alternative recovery option:

ROM Manager (in the market)

ALWAYS DO A NANDROID/CLOCKWORKMOD BACKUP!

It will restore everything the way you had it if you F something up.

Want to go back to original shipping, but followed this guide, downloaded the linked file and can’t find the image files?

They’re not in that file. I don’t know why. Go here and download FRG33, decompress it and use the contents to follow the tutorial

Are you getting a “verification failed” error when you try to apply an update.zip in recovery?

Mount your SD card to your computer, download whatever file you were trying to apply directly to it (don’t download it and then drag it), and rename it to “update.zip”.

If you’re using Windows, make sure “hide extensions for known file types” is unchecked in your folder options within the Control Panel. You’ll keep having problems if it’s named “update.zip.zip” and you didn’t realize it

If you're still having problems, try this download of the stock FRG83 update.

<Added 11/18> I had another facepalm moment. If you downgraded back to FRG33 and you get an "assert failed" error, flash the recovery.img from that FRG33 package you extracted. (found this solution here)

Did you flash a ROM or go back to stock, start up your phone and noticed that you’re stuck on Edge?

Go to Menu>Settings>Wireless and Networks>Mobile Networks>Network Operators>(choose your carrier), wait.

Trying to copy something from your SD Card to /system/app (for instance)?

If you use the “cat” command, DON’T FORGET THE “>” SYMBOL. Nothing awful happens as far as I know, but it’s unnerving to watch the terminal puke all over itself.

cat /sdcard/thing.apk > /system/app/thing.apk

If you’re new to Linux and/or Android and are removing apps:

BE CAREFUL with the “rm” command. Once it’s gone, it’s gone.

You can always rename (technically, "move") the files instead:

mv /system/app/thing.apk /system/app/thing.apk.bak

Switch the commands to get it back

mv /system/app/thing.apk.bak /system/app/thing.apk

And don't forget to mount /system as read and write. To do that:

Windows: (must have drivers installed, Nexus One drivers are in the SDK)

adb shell
su

Linux: (no drivers necessary)

./adb shell
su

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

Don't forget to mount /system as read-only when you're finished. To do that, use the same code but replace "rw" with "ro" (without quotations of course)

Having trouble connecting with adb?

In Linux, you need to be in the SDK directoy (mine is in ~/AndroidSDK/tools). In Windows, you need to have ;C:\AndroidSDK\tools in the system path, within Environmental Variables (right-click on Computer>Properties>Advanced>Environmental Variables)

Unplug the device

In Linux, cd to ~/AndroidSDK/tools (or whatever you called it) enter:

sudo ./adb kill-server
sudo ./adb start-server

Plug in the device

sudo ./adb devices

In Windows:

adb kill-server
adb start-server

Plug in the device

adb devices

Device not found?

Did you enable USB Debugging in Menu>Settings>Applications>Development?

Trying to install an .apk but it just won’t work?

Try the “adb install” method, or push the apk to /system/app. If the app force closes or doesn’t work, just remove it

rm /system/app/thing.apk

Using Ubuntu (or another Linux distro), trying to mount your SD through Amon-Ra's recovery, but it won't mount?

Disable USB-MS toggle, unplug the phone, reboot your computer, try again.