Follow below steps to capture the gateway debug logs,
1. Insert Micro-USB cable between gateway USB debug port and your PC.
2. Open debug console(Using Teraterm in Windows or Minicom in Ubuntu) in your PC.
3. Power on the gateway.
4. Log in to the gateway console using below credentials,
5. Dump logs on the console by using below command,
$ tail -F /var/log/VMGFull
6. Copy all the logs on the windows by right-clicking and selecting "select all" option and then "copy" option and dump it into one text file.