Responder a:Display discoloration after 2 months usageI had the same problem some days ago. The black/violet spots will probably widen until the display turns completely black. I was forced to change it, and it's considered to be out of warranty (at least by Samsung). Maybe it was not your fault. My phone broke even though it did not bother or anything else that could had damage it
Responder a:Battery compatibility between S5 vs S5 NeoYes, the battery of the S5 is compatible with the S5 Neo. A Samsung staff member wrote this in a forum, so I guess (and I hope) it's a good information!