It may also be good to mention that, as far as I know, the "hack" or unlocking always has worked, once the correct serial number is entered into the correct keygen and then into the oscilloscope.
The best way to find out the scope serial number is to look on the back of the scope where the SN is listed on the label. This can be confirmed by asking the scope itself but the numbers may be hard to read on the screen.
The best way to generate the unlock code is to _download_ the actual keygen from the riglol site, which version depends on your OS so just get them all, and run the keygen locally, using the code DSER to unlock all options + 100MHz bandwidth. The DSER code is not documented in the keygen help screen but don't worry, it works.
The best way to get the generated unlock code into the scope is to use telnet or other terminal emulator over the LAN, and copy-paste the necessary key into the terminal application, using the correct SCPI commands to talk to the scope. Alternatively you can enter it manually into the scope's little keyboard but you will get locked out for 12 hours actual runtime if you fail three times.
Again, as far as I know there are no known reported cases of the unlock procedure failing when properly applied, nor has anyone bricked their scope or failed to "re-lock" (remove options, reset to 50 MHz bw) when required, by using the proper procedure, the SCPI commands and the LAN connection.
Doing the "factory reset" procedure using the front panel buttons does not affect the options or the bandwidth.