heroB+, J3455 cpu, Linux, connect to 2nd display

Laptops HeroBook Plus
1

Hi,
I am trying to connect my HeroB Plus to another display. I want to either extend the laptop screen or just use the larger screen.

I used the mini HDMI out of the laptop to a normal large hdmi port of a tv and then to a portable screen.

In both cases, with the cable in place, i restart the laptop. The 2nd screen ONLY shows the start up screen but goes black and the laptop comes up when the OS starts.
When I go into display options, I cannot see the 2nd screen.

The cable is obviously good but I presume it is either the BIOS or the way the hdmi port is built ?

Any ideas please ?

2

Search for a tutorial on Google.

3

I have obviously done that already.
Do you have an experience of this particular problem ?