Error code occurred during ECU Upgrade (5021-FF-0025)

Symptom: 5021-FF-0025 error code occurs when trying to upgrade ECU

Cause: May occur when the ECU app security certificate is invalid

Resolution :

Tablet Settings - Select GDSM(Smart) or KDS(2.0) app > Storage > Delete Data.

And after restarting the app, check if it works normally.