I am facing the similar issue and did all the testing but no success. We are getting below message on console and found there is a bug (CSCuu00752) in switch . Hence we are going to replace the same we did the power cycle work around provide in this bug but issue is still same.
%ILET-1-DEVICE_AUTHENTICATION_FAIL: The FlexStack Module inserted in this switch may not have been manufactured by Cisco or with Cisco's authorization. If your use of this product is the cause of a support issue, Cisco may deny operation of the product, support under your warranty or under a Cisco technical support program such as Smartnet. Please contact Cisco's Technical Assistance Center for more information.