I've been trying since yesterday to install Manjaro on an old laptop using a Live install USB stick. The screen shows the usual BIOS / HP screen and then it apparently tries to boot the USB. All that happens is the word "GRUB" appears at top left of the screen and then nothing. The USB stick shows no flashing light, indicating no transfer activity. I never see the initial Manjaro screen.
A few more bits of info: I've taken the same Manjaro USB installer, and booted it without problems on an even older laptop (which has far too little RAM to use). So there doesn't seem to be anything particularly wrong with the Manjaro USB installer. Second, I ran an Ubuntu USB installer on the laptop that won't boot the Manjaro USB. After retrying a couple times, it eventually loaded Ubuntu Live (I've tried to load Manjaro a couple dozen times at least). Third, the antique BIOS on this (Insyde F.1C I believe, on a HP Pavilion laptop) does not have any UEFI or EFI options nor a Secure Boot option. There's a place to set a boot password, but it is unset. Finally, once I see the word GRUB, the system seems inert--ESC and ctrl-alt-F2 have no effect.
I'm guessing the problem is the BIOS just doesn't do well w/ USB boot-ups and in particular whatever is in Manjaro. If anyone has thoughts on other things I might try, let me know.