Quoting the gitbrew website:
This hasn't been 100% tested, though we're looking for people to try it to see what bricks it will actually fix.
1. Put both files into the root directory of a flash drive.
2. Put the dongle into the ps3 while it is off and start it.
3. If the flash drive is activated it can be fixed using this.
4. If it however does not, the only fix for it until a software side is found is a hardware flasher.
Please note this will ONLY work on 3.55 and lower, and in only a small amount of cases.
Thanks to hvckz for the news update!!