I'm in the process of installing the Ubuntu image onto my Nexus 7 following these directions. I am on the step 4 and typed in phablet-flash -b and it downloaded some files, erased 'system' and is now on sending 'system' (92311 KB)... However, it has been on this step for about 3 hours now. I am assuming it shouldn't take this long so how can I go about getting out of this and restarting the flash without bricking my device?