Go to MAINTENANCE
> Diagnostics > Diagnostics > Collect and click Collect Now.
the collection is done, download the file at MAINTENANCE > Diagnostics
> Diagnostics > Files.
the tar file and open diag_zysh_common.dbg to find the oldest system
time you press the RESET button is 1-2 minutes prior to the time flag.
this example, I press the RESET button at 15:53. The time flag of the oldest
system log is 15:54:25.