iPhone 6s touch ID fail after lcd replacement

I have an iPhone 6s and I replaced the lcd, when I powered on the device everything was good for about a day. It worked fine, suddenly a message appeared "unable to setup touch ID". Made a hard reset but nothing, I restore all setting but nothing, replaced the lcd but nothing, restore to factory setting but nothing. Then I decided to install the broken original lcd but again NO TOUCH ID. I have done everything I read in other forums, I inspected the connectors in case of damage but Iooks fine, then I tested the lcd in other iPhone 6s to see if this is going to work there and worked just fine in other iPhone.The touch ID menu IS NOT GREY, I can select menu "add fingerprint" but then returns message "touch ID fail" I'm desperate, I don't know what to do and I really need the touch ID. I use it for some account sites and bank sites. This strange behavior I don't know what to do.please I need advice from someone had fixed similar issue. Thank you