Rooting an encrypted Android device

I wanted to root my Nexus 7, so I installed the right image and zip. But then the device didn't work any more. I think it's because the device was encrypted, and somehow after rebooting, the thing got stuck. I managed to get the right factory images from Google (I didn't backup the system, which you should always do), my defice is "flo" which is "razor". After I got the device back to a factory installation, rooting the device with clockworkmod was easy. Now I'll encrypt it again.