I have a Dell S4048 switch version 9.14(1.1) in a stack and last week I replaced the stack-unit because it was failing to respond. I tried to console in to the faulty device, but when I connected to the port nothing came up. 

Yesterday the same thing happened with the unit that I replaced just last week and when I tried to connect via the console port nothing came up. 

I'm using a QSFP 40GBASE-CR4-3M cable for the stack cable. 

Has anyone had this problem before with a stack unit?