HTC One S seems to be in some problem as some early customers have alleged that the micro-arc oxidized; the supposedly rugged finish has been surprisingly easy to damage. At an early stage it would be not sure that what kind of problem is it but later the company put out a brief statement that they are looking into the matter:
HTC is committed to delivering a high quality product and great experience for all our customers. There have been a few, isolated reports of this issue. The finish on the One S was laboratory tested as being at a hardness similar to ceramic. While that’s hard, it doesn’t mean it’s impossible to damage. Regardless, HTC takes quality very seriously and are providing all customers with an immediate fix and we are implementing some small changes to ensure customers do not experience this issue in the future.
The company says we are working on to resolve the matter as early as possible by “providing all customers with an immediate fix”. The company further says that simply return the One S to the store where you bought it within the DOA period (typically 30 days, though it varies by country). Beyond that, HTC says it’ll be happy to fix the phone under the standard warranty terms.