Here3 GPS not updating firmware using Passthrough

I have a Here3 GPS. I want to use it with RTK so I brought the Here+ Base station. I updated the firmware of the base using the u-centre application. When doing the same for the Rover, the firmware update always fails. It is always stuck with “retry poll” and then it says “update failed”.
I am stuck on this for a few weeks now. any help would be appreciated.
I followed the steps for the update exactly as they are from here -
Here 3 Manual - CubePilot.


Can you share some screenshot about this? Like the error message from u-center.

Also, you may verify if the baud rate is correct. Sometimes the chip went to different connection baud for some reason.
You can do this by checking in u-center > View > Message view > MON > VER. If the version info are correctly shown, the connection is good.