I had to do a firmware update with my G80-8113 too. There was something that popped up, but for the life of me I can't remember what it said. I'll have to look it up when at home. Do you have a screen shot of the error? It might be that you have to point Cherry Tools to the correct firmware file, since it's got a whole folder full of them and doesn't seem to know which one to use for which board.
At any rate, it is possible to update a G80-8113(mine was a HRBUS, using PS2) using the v5.8 Cherry tools. This was even with Windows 7 x64.