Ctrl+Break could be tricky if not entered at the proper time while the router is booting up. I recommend you send the command using your Console application (such as Putty, SecureCRT, etc) which I am sure you are using.
If you have another 3825 or similar model, you can switch flash cards and see if that'st the problem. Be careful if you are doing this with a production router since your configuration may get corrupted. Make sure that the flash led is not lit which means that the flash is not being used before removing it.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...