Boot loop if both front camera and home button is connected

Hi,

I have this strange problem.

I did an iPhone 7 screen replacement. After two weeks my customer said the home button and touch id won’t work. One day later it went into boot loop.

I disconnected the front camera flex, and then it started, but no home button functionality. I plugged the front camera flex back in, and disconnected the home button. It still booted. But if both the front camera flex AND the home button is connected at the same time, it just goes into boot loop.

I’ve tried this:

1. Changing to several different screen, both original and copy.
2. Connecting another original front camera flex from a working phone.
3. Disconnect one flex, start the phone and then plug the flex back. The phone doesn’t turn off or change behaivor doing that.
4. I’ve searched with Google, iFixit and YouTube, but can’t find a similar problem with a solution. I’ve also tried to serch within the schematics for iPhone 7, but can’t find anything obvious that those flexes has in common that should cause this.

If I disconnect the home button and start the phone, the ear speaker work, but not the front camera, proximity switch or the light sensor.

Any suggestions?

Thanks in advance!