I am no way responsible to what happens to your phone, Know that what you do can cause harm,very unlikely to
happen but still take caution
Your Phone needs to be rooted
and Need a File manger that can get root access or knowledge of ADB
Go to the root directory /system/customize/resources
and the file/mp3 you want change is "AATTSonicLogoNoSnap_Retail.mp3"
grab a MP3 that you would like to use as your bootsound. It has to be about 3secs long. Edit your Mp3 with your Favorite mp3 editor.
Once you have your custom MP3 rename your mp3 to the same file as "ATTSonicLogoNoSnap_Retail.mp3"
Place it into the same file directory where the orignal /system/customize/resources it will ask to overwrite choose yes once reboot and you should here your sound!
i have attached the "DROID" sound for those wish to use that, Just unzip it.
im willing to take request if any dont feel like making one or dont have mp3 editor
Thanks for reading!
And those what to change there Bootanimation and BootDown Animation
you can use any others from other threads just make sure its this size
Bootanimations are here too but i dont know the scale of them
due to copywrite issue i can not do music/songs