Ouch! A battery pull is not going to do anything because there is no OS loaded on your device. This happened to me a couple of upgrades ago and before I could get the OS to load I had to use jlcommander to wipe the device. Hopefully it completed the back up process so you'll be able to restore your apps, etc. once you get a functioning BB again.
So here's my advice ............ reboot PC (in case it is a windows issue) > wipe BB with jlcommander > launch loader.exe to reload OS. It might not be a bad idea to re-download the firmware to ensure you have a good copy.
Good luck and let us know how you make out.
__________________ Regards, Jag "Torch 9810 + Playbook 64gb"