I have some strange feelings ..
when i put the phone on the table or bed.. and press the screen with my finger , i have to use more pressure to press some buttons.. but when i touch the back cover with the other hand.. it's more easier .. When you open your backplane you can see some golden contacts that provide electrical signal between backplane and the phone..
And for this reason i think that we have to order original backplane in the future..
Sorry for my english..