Linux Lite 5.0 USB only shows "grub>"

[Moltke]

Thank you for the quick response!

I tried again with Etcher. Windows can't read the USB drive after flashing. My BIOS did recognize it this time and I managed to run LL (woohoo!). But then after rebooting my BIOS stopped recognizing the USB drive as bootable (never had this issue with other distros).

So it kind of works but requires some retries and Windows doesn't like the image at all. I don't know if it's a problem with Etcher or with the image. Other distros boot perfectly from USB on my machine so it may be unlikely that it's a local issue.

Any ideas? Does anything of what I mentioned sound familiar?

That is regular etcher behaviour; it formats the USB so Windows can't see it. I suggest you use rufus https://rufus.ie/ to burn the .iso in Windows and ty to boot again after doing so. I've used it and it's worked so far, haven't tried with LL 5.0 though.