I just bought my first xhp70.2 and it looks burnt in the middle of the back. Is that normal, or did they send me a used one?
This should be normal or at least I observed on many leds I used and they had no problem.
Maybe someone else can explain the cause. I suppose it is moisture?!
By the way, welcome to BLF, Vengeance. 
Thank you!
I bought it from DigiKey to make sure it was authentic. I also bought a cheap one from AliExpress to compare(1/7th the price). I’m sure that one won’t get here for a couple months.
Odd - I haven’t seen this before, but I’m also interested in the cause!
At least so that when it happens to me, I won’t be too alarmed…
I emailed them asking about it 9 days ago and they still haven’t responded. I just sent another one. I plan to overdrive it and don’t want them to say I did it during use, so I haven’t used it yet. The “burn mark” might also be a thermal barrier, like carbon or oxidation, which would be bad for overdriving.
They just shipped out a new one and said “sorry for the defective product.” They didn’t say what it is or if it’s normal.
I’ve seen it here before.
It is only tarnishing, due to the hole on its package.
The new one is likely to be the same.
Yeah, the second one has it too, but half the size. I’m going to sand one down to be sure it’s not a thermal insulating layer.