I have an Acer Iconia Tab A500 that came with Android 3.x installed; most recently (after system updates over the last 9 or so months), it was running 3.2.1. I use the device for testing apps; the device is not rooted. I turned the device on today for the first time in awhile. Without thinking, when notified with there was a system update, I downloaded the update. Turns out it was an OS update to ICS. I want this device to remain on Android 3.x (I already have 4.0 & 4.1 devices). But it is now running 4.0.4. I did the factory reset, but that did not reset the OS back to 3.x. Is there any way to revert the change (go back to Android 3.x on the device)? Thanks in advance.