Sure will do 
I would also like to share what may or may not be the same issue as the above.
On highest mode, whether with 14500 or AA battery, my newly-received XT1A (that was a few weeks ago) also has flickering. Unlike the above, the flickering does not stop in 10 seconds or 20 seconds, like what others mentioned. Instead, the flashlight will flash (like strobe) for a while, and sometimes go back to flickering. It sometimes can change modes but sometimes it’s more difficult to change modes with the paddle-switch, when this happens.
I have show this issue (made a Youtube video) to the online store where I got it, and they asked me for the serial number on the body tube. After giving them those info, they said that the problem is the tailswitch (body tube+tailswitch assembly). They then shipped me the replacement body tube/tailswitch assembly, which I just received.
After using the new replacement tube/tailswitch — the flickering does not occur anymore whether on 14500 or AA battery. So, it is indeed a body tube/tailswitch problem that’s causing the flickering issue.
Does the Klarus XT1A really have battery reverse-polarity protection?
I made an accidental “user-error”, I inadvertently placed the 14500 battery backwards on the body tube. When I clicked the button to turn on, there was no light (maybe tried clicking 3 times), so I unscrewed the body tube and noticed I had the battery backwards — when I placed the battery in the correct position, the flashlight now only blinks). Probably the driver got damaged by incorrect battery placement.
So this seems to mean the XT1A doesn’t have battery reverse-polarity protection?
I have no idea, that isn’t something I usually test for.
I already have my XT1C! However, as I didn’t dislike that much the beam it produces, I didn’t try to take the bezel out! I guess I will not consider that 
Still, it is glued!! 
About the Reverse Polarity Protection, asked by d_t_a, I didn’t test it on mine. Actually, after seeing his statement, I got afraid of putting the battery reversed :zipper_mouth_face: So i guess I won’t try it! Still, that information is not available in the User Manual (as far as I could perceived)! 
According to the Klarus website, the XT1A is supposed to have reverse-polarity protection. It is one of the highlighted points listed on the 10th splash screen under Multi-Safety Protections.
Hey guys i received my XTA1 last week also had this light flickering issue when powering with the primary switch, revived an email back asking if i had made sure that it was screwed together tightly. I gave it a decent twist and problem was solced.as i isolate by unscrewing a quarter turn ill just need make sure its tightly screwed together.