Feedback on the Dell Latitude 5400

Hi,

I received a new Dell Latitude 5400 shipped with Windows 10 64-bit.

I Had to install the late Linux Ubuntu 20.04.1 LTS on it, with the LVM encrypted partition option, and the installation went well.

After starting using Ubuntu, I had 2 problems:

1) Trivial boot with Dell logo remaining and not going forward. forced to reboot manually once or twice to go through

2) I tried with the Dell certified Ubuntu version 18.04 LTS for hardware, as stated here : https://certification.ubuntu.com/hardware/201902-26851

Among the updates proposed, I had the BIOS updated from 1.7.3 to latest version 1.9.1 => this seemed to solve booting problems !

3) But, now I have another problem : the PC is totally freezing without responding, IF I unplug the DOCK Thunderbolt power cable 0_0 => Yes, the PC needs to be connected to Dock, otherwise it completely freezes after eta 5 min, not responding at all...

IS it a Hardware/Software issue ??

N.B. : Hardware info. https://linux-hardware.org/?probe=869749e656

Thanks for your feedback.