FYI: It turned out to be defective hardware and all the UPS units were replaced. If someone has older UPSs units that do not have service tags, I'm not sure if its the same issue since it was isolated to a particular manufacturer with a particular bad batch.
In addition, I have older UPS units than 2012 and they do have service tags under their panel but they are not the 2700W version, they are the 4200W version.