This is taken mostly from a thread showing how to change the startup sound and image on the LG Optimus. http://androidforums.com/lg-optimus-m/228290-metropcs-hello-hello-goodbye.html
I did this on my MetroPCS Ascend. I assume Cricket would be the same if not very similar.
1. Download and install Root Explorer (must be rooted of course.)
2. Find a compatible animation (I used http://www.vopinc.com/files/Android/GDbootanimation.zip) which will be renamed "bootanimation.zip" and an ogg sound file (I used http://www.moviesoundclips.net/tv1/tng/braincells.ogg)which will be renamed "bootStrapSound.ogg".
3. Navigate to /system/media directory using Root Explorer and copy the animation over the default file (save the default somewhere if you wish)
4. Navigate to /system/media/audio/ui directory and copy your sound file over the default file (again, save the default if you wish).
I've tested this myself and it works like a charm. No more annoying MetroPCS logo and sound.
I did this on my MetroPCS Ascend. I assume Cricket would be the same if not very similar.
1. Download and install Root Explorer (must be rooted of course.)
2. Find a compatible animation (I used http://www.vopinc.com/files/Android/GDbootanimation.zip) which will be renamed "bootanimation.zip" and an ogg sound file (I used http://www.moviesoundclips.net/tv1/tng/braincells.ogg)which will be renamed "bootStrapSound.ogg".
3. Navigate to /system/media directory using Root Explorer and copy the animation over the default file (save the default somewhere if you wish)
4. Navigate to /system/media/audio/ui directory and copy your sound file over the default file (again, save the default if you wish).
I've tested this myself and it works like a charm. No more annoying MetroPCS logo and sound.