The Faulty 5Ci was a concern and surprise ; However in the communication with Panda I was assured and informed a faulty batch of 5Ci keys was produced ,and under Warranty I was able to return a new Yubikey for a replacement. Panda regularly briefed the tracking of new key . In addition Panda is a distributor ,but I was able to glean basic information practical- as was purchasing a 2nd key as backup if I was unable to access my 5Ci key ; However Pandas main business is to provide a Service as a Distributor. In all the Panda representative was polite and reassuring to the problem of a faulty 5Ci , and the replacement of a new device. Thanking You PANDA.