Where can I find the OTA update file? I'm trying to locate the zip file that contains the OTA update for my Droid Bionic.  Right now, its failing to update, and every time it fails it deletes the file and I need to re-download it (takes a long time).  I was hoping to save off the update so I could try a few things on my phone and try the update.  I read online its somewhere in a /cache directory, however I dont see anything at all when I mount it to the PC and do a search for cache or even "*.zip".  Does anyone know how I can find the zip file?  Maybe I need to change the PC settings or something to search for it (I have changed the folder settings to view hidden files and system files).
Two pieces of ground I want to cover here:


/cache is typically a separate partition on your device, which wouldn't be mountable by a PC via USB, which is why that isn't working. The USB connection generally accesses a directory named "sdcard" (or similar) which is used as an external storage device, although this storage area doesn't have to be physically external to the device (it may just be a partition named /sdcard rather than a physical card).
If the OTA is in /cache then you should be able to find it with a file explorer or shell on your device. Once you've found it, you could simply move the file from /cache to your external storage and then copy it over USB. You'll need root in order to access /cache, though. There are a number of file explorers that support root access, but I personally use ES File Explorer.