Good day friend
The guarantee would be fine but I don't know if it is valid in your country after having restored the system 3 times
I would start by trying to lift the key and carefully clean the contact with a little isopropyl alcohol here I leave you how to remove the keys
https://www.google.com.mx/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DLU9wUhAhDVc&ved=0ahUKEwisicCXu4zYAhVB_WMKHbfKAzAQwqswg0ggwgdwgdgwdwpwdwpwdwpwpfdwpwdwpwdwpwdwpfdwpwdwpfdwpwdwpwdw5fewkwpwdwpwdwpwpwdwpwdwp3d3d2