I'm not as familiar with Pop OS but it uses systemd boot as bootloader which is pretty simple. As the above commenter mentioned can you give a screenshot of any errors or where the boot hangs? Or if there's just a black screen let us know. If it's an early boot issue may need to just boot to live USB media and check the bootloader files and reinstall packages if any files are missing. People more familiar with systemd-boot and Pop OS may have better info.