iPhone 6 Home Button Connection Issue

After replacement of iPhone 6 Home Button with a iFixIt replacement part the Home Button and Touch ID work after connecting all plugs to the mainboard. But after assembly of the upper metal bracket to fix the plugs to the mainboard, the home button does not work anymore. After trying some times I luckily found a position where it worked with assembled bracket. Happily I put everything together but after some hours its lost the connection again. I’m not sure where to search for the mistake. Lower plug connection and Home Button itself seem to be working fine, the problem seems to be somewhere in the upper connection area .

Any suggestions?