Few bits.
Meticulously go through your BIOS settings (UEFI, CSM, no fast boot, and at least on my motherboard EFI shell, etc.).
And the big elephant in the room- Solus live USBs seem to be VERY finicky (I almost have a complete set!). If you have a few manufactures lying around, try them all until you get one that works (SanDisk have been the only ones that have played nice for me thus far, but YMMV).
And the usual voodoo (trying different usb ports, make an offering to the tech gods, trying on different machines to isolate the problem).
But once you get one, those suckers are very useful.
And then, you can go over the posts about boot rescue and updating from live USB.
