OS won't boot from USB HDD, bootloader or PC problem?

Question

Hard disks

Hello dear Toaster users, I again continued my "experiments" with USB HDD and laptop.
USB HDD with installed OS (I tried Ubuntu, Windows 7, Windows 10 - the result is the same) is connected to the laptop.
When booting the laptop, a black screen appears and "_" or "." blinks on it. (if you switch to the MBR there will be a dot)
I could not determine what the error was and how to fix it. Googling didn't help.
The laptop itself works well. Maybe the USB HDD has something to conjure with the bootloader?

Answer 1

Not all OSes are loaded from USB 2.0 ports, almost no one is loaded from blue (USB3.0) ports.
And what caused the need to boot from USB?

Answer 2

How old is the laptop? If a lot, then maybe with a PC, but hardly. By the way, do not forget to change the boot order .

Answer 3

there are laptops with a ban on foreign OSes, and even this is not written in the BIOS, I came across laptops where the ban, for example, was removed by pressing the escape key 8 times after turning on the computer and loading the BIOS, especially laptops with a GPT hard disk structure, those are still dancing there are with a tambourine, look more carefully, Seeker will find it! in general, look specifically for your brand and model, but in general, drop the brand and model here, maybe I’ll look for it at my leisure and tell you