pretty sure you are on your own there for a dead br600 in 7 hours. I just bought one last week, mainly due to the lighter weight and the fact that they are quieter. It probably has close to 7hrs on it so far and it seems to run ok, certainly not slowing down productivity that's for sure. I will probably buy another one, just because they are more comfortable to wear too. Sounds like you have a lemon.
fully lic. and ins. 10yrs exp.