Installing Linux Lite on HP Probook 6550b

[Peejay]

I have bought a used HP Probook 6550b in order to install Linux Lite. It has come with Windows 10 Pro installed but I cannot find out how to turn on Legacy mode so that I can boot the LL 4.0 USB. I can access the BIOS/UEFI with F10 and creating a password has enabled me to access the Security tab. On this there are settings for Legacy mode which are not greyed out but changing them seems to make no difference. I can find no reference to Secure Boot in the BIOS/UEFI but there is a section on TPM which seems to stand for Trusted Platform Module and I am assuming this does the same job. In my Acer Aspire V3 I had to access the BIOS via an entry in Windows Advanced Settings, but this version is different (perhaps because later, or HP not Acer, perhaps because Pro version of Windows).I'd be grateful for any pointers or suggestions on how to activate the Legacy Mode. There are a couple of successful entries for the 6500 series of Probooks in the hardware db, so I live in hope!
Thanks

[Peejay]

I am pleased to advise that I managed to run the LiveUSB eventually and have now installed Linux Lite 4.0.I found that not for the first time, I was making things more complicated than they really were. References to Trusted Platform Module led me to believe that this was HP's version of Secure Boot but it isn't and in fact the default setting for it is OFF.
Just in case anyone else gets bamboozled by this too, here are the steps I took:
Enter BIOS/UEFI by keying F10 on startup. In Settings click Yes to restore System Settings to factory defaults. NB there are two Default resets possible and I left the BIOS settings untouched.
On reboot you then key F9 for the Boot Menu. This can look a bit weird but there is an option for System Update Disk and you can select that. You may find you need to play around with the Legacy Boot Devices in the BIOS to get this to appear but I found it would not respond to a USB stick and in fact a USB device never showed on the Boot menu.
It will though boot from a CD or DVD but I didn't want to create a new DVD so I opted for the Plop booter. (see https://www.plop.at/en/plopkexec/index.html). This is a tiny program that locates Linux systems ready to boot. It was a bit of a juggle to get it to work because if you expose the LiveUSB to the BIOS it just stalls. So the trick is to have the stick ready and as soon as the CD is initiated insert it into a USB port - the one adjacent to the DVDROM is the handiest. Plop then identifies Linux Lite, you select it and away you go. Leave it too late and plopexec does the scan too quickly to notice the LiveUSB and you have to start again, lol.  The actual installation was a breeze but getting to the point of loading was unexpectedly difficult.
The laptop itself seemed very good, a nice clear screen, solid keyboard, positive touchpad, a decent i3 processor and 4Gb of RAM, and there's provision for a dock too, if that's your thing.

I swapped a SSD into the machinetoo  and it goes really well.

[Valtam]

Thanks for sharing the solution.