Not having been there it's hard for me to say, but I think they could have a case with clause 6.3
In Reply to Parent Post by ISO 9001
The organization shall determine, provide and maintain the infrastructure needed to achieve conformity to product requirements. Infrastructure includes, as applicable,
a) buildings, workspace and associated utilities...
If the power failed and could cause problems with the work, customer schedule, etc. then it might be considered a nonconformity.
Each audit should have a defined scope agreed between the Certification Body and the company. They shouldn't be including requirements of other standards in an ISO 9001 audit unless there has been a prior agreement to do so.