There are many reports of systems booting to a blank screen, which is probably a graphics problem. In such cases, you may be able to get a terminal by entering <Ctrl-Alt> N, where N=2, 3, or 4. Pressing escape when the system starts to boot may let you see kernel messages. From the grub menu you can edit the kernel command-line to remove “rhgb quiet” to see the messages.
In a terminal: man journalctl. A problem with journalctl is that the lines can be very long. On strategy is to run journalctl and scan for messages related to a problem and select a string specific to the problem. The capture those lines in a file:
$ journalctl -b N | grep string_specific_to_the_problem > string_specific_to_the_problem.txt
You then edit and annotate the file and paste into a forum post (bracketed with triple backquotes).