HERE + RTK firmware update ok but doesn't work

Hi all,

It’s not a first time I try to update the firmware 1.30 or 1.40 from uBlox on HERE + RTK v2 Rover module. Every time I try, after a good process described on documentation (green screen on process), the module don’t work and don’t want to connect anymore with COM port with USB dongle available on HERE+ v2 version.
DOC Link :

U-Center used is the last one v20.01, firmware do not appear on U-Center and I try to download manually.
At the end of process everything is “green” on screen but the ROVER HERE+ don’t want to connect with U-Center. I just see the port COM 9 available, I press Connect (green color on top left) but grey color on Bottom appear. Tryed with different Baudrates. No connexion.

If I do the same with a Drotek module, same inconvenient. It seems like no bootloader or configuration inside after installing an update.

I lose the capability to connect the GNSS module to U-Center.

Questions :
1 - Does someone experience same problem ?

2 - Using U-Center, do I need to save a Here+ BEFORE to update the firmware ?

3 - Why my U-Center v20.01 dont show me the right firmware on TOOLS MENU, Legacy Firmware Update automatically ?

4 - No idea how to recover this problem with no connexion with the USB DONGLE available on Here+ v2 version.

Thanks a lot for your helping hand.