It's not very likely that your sd-card is dead because it is just a partition, so if your sdcard is dead your phone probably wouldn't work at all.
Normally I should say that it would be a firmware, partition problem or a bad flash but the RUU should have fixed that.
I have two question if the answers are both yes than i have no other idea's and would advise you to return it for warranty and hope for the best.
1. Did you run an signed RUU.exe file. The filename should look like something like this: RUU_Ville_U_JB_45_S_HTC_Europe_3.16.401.8_Radio_1. 11.50.05.28_10.27.50.08L_release_301814_signed_2_4 .exe
2. Did the RUU run without any errors?
You could also try to run the RUU one's more or try another RUU, you should get the right one matching provider and country/region.
Here is a list of RUU's for the htc one s:
One last thing did you change your CID, that is also known to cause problems.
If you want to return it for warranty then I wrote a guide how to get your phone completely back to stock:
You could also just relock it and then return it but they maybe let you pay then.