When in doubt, try the different options... learn what they do firsthand. And then, if there is something you still don’t understand, after you have bounced around in the menu some and consulted the manual, there’s always this message board. I found part of the fun of owning a new radio with a steep learning curve is exploring the various options.
As for the display backlight blinking out, your question has been answered by another. The reason the radio doesn’t scan could be any one of a number of things. Check to see that everything entered has a “Service Type” assigned to it and that those Service Types are turned on. Another possibility is that the scanner will not stop on channels or talkgroups of some commonly used forms of encryptIon. So if you have a trunked system that totally encrypted such as the Florida Highway Patrol and another conventional channel such as the local fire department, you could conceivably wonder why you are only hearing the FD. Those are just three of possible reasons for your issue. Not to worry, keep hitting up the group here with what you need help with. You may get a couple of “Read the manual” comments, (which really are justified-you should read the manual... and explore the menu first), but others will post an answer you can use.