It's always a good idea to clean and lube a new light. All the fumes and stuff at factories can leave thin filmy deposits on battery contacts points. It's preferable to use an actual contact cleaner, like Deoxit, but yes, common isopropyl alcohol, the kind that is probably in your medicine cabinet, will work in a pinch.
I don't have this new SS E05, but I'll bet it's similar to most screw down switch type lights.
The trick is to only put a little bit on the Q-tip, and then hold the head of the light with the opening facing down (LED facing up), and then gently clean the positive contact point in the head, not letting any drip down into the head onto any circuits. While you've got the head there, go ahead and gently clean the thin metal contact ring that is around the edge of the head. The ring outside away from the positive contact point. That is where the battery tube completes the negative part of the circuit when you screw the parts together.
Then clean the negative battery contact point at the bottom of battery tube, AND, clean the actual exposed top end of the battery tube, which is the part that makes contact with that thin outside ring in the head when you screw the battery tube and the head together.
One of the reasons we like these kinds of lights (with the screw together switching), is that it really is simple and reliable, and if there is a problem, it's usually a simple fix with a quick and easy cleaning.