This worked 2.3.6/6.12.173.xt912.en.US
This also worked for me with the Razr Maxx, version 2.3.6 of android and 6.12.173.xt912.verizon.en.US. OP did not work but this one worked like a charm, 3 total reboots and about 5 total minutes. Thanks!
Was having no luck on a new-to-me RAZR with 2.3.6, then I found and tried MotoFail, worked like a charm.
Found the link here: http://vulnfactory.org/blog/2012/02/11/rooting-the-droid-4-a-failed-bounty-experiment/
Direct link: http://vulnfactory.org/public/motofail_windows.zip
This also worked for me with the Razr Maxx, version 2.3.6 of android and 6.12.173.xt912.verizon.en.US. OP did not work but this one worked like a charm, 3 total reboots and about 5 total minutes. Thanks!