Update: there is a press release explaining what happened:
The crucial information isDuring commissioning (without beam) of the final LHC sector (sector 34) at high current for operation at 5 TeV, an incident occurred at mid-day on Friday 19 September resulting in a large helium leak into the tunnel. Preliminary investigations indicate that the most likely cause of the problem was a faulty electrical connection between two magnets which probably melted at high current leading to mechanical failure(...)
In fact, warming up and cooling of one sector usually takes 3 months, so there is little hope for a beam before the winter shutdown (end of November).(...)it is already clear that the sector will have to be warmed up for repairs to take place. This implies a minimum of two months down time for the LHC operation...
Update 2: :-(