replacing board to home button flex cable on back plate.

"you will need to shield the ribbon cable again on the back plate.

when you remove the old ribbon cable you ruin the shielding in place; without that shielding you will experience issues with odd screen colours and with the digitiser sensitivity (especially in the upper third)

for shielding you can use standard electrical insulation tape.

just cut a strip long enough and tape it along the length of the ribbon cable.

also be very careful with the lcd connector; its very flexible and has to be exactly in place for your screen to display perfectly; usually it gets bent slightly when you remove it; so just check it; carefully flex it back and be 100% sure its sitting perfectly in its slot before pressing it down again. even a slight misalignment will result in pixilation, discoloration or an odd stripe.

dunno why but the iPhone 6 and 6+ lcd connector is just rubbish."

I did the same thing (tore flex cable during disassembly) I replaced it fine with no errors. Only problem was that I damaged the black backing tape that covered the flex cable, now I have a yellow stripe visible on the screen display, not sure if it is related to the damaged black backing tape, but otherwise functionality is fine.

Yes if in any way the mainboard is unable to communicate with the Touch ID button or the authentication fails, you get error 53 when restoring iOS.

"I imagine the cable is simply that, a cable. But it's an apple device. A quick google indicates the error occurs when the sensor is replaced. Not so much on the cable.

If they device is under warranty, take advantage of the warranty."

"I ruined the ribbon cable when trying to remove the home button. I just bought the shield plate with ribbon cable from amazon. Will the home button (original) works as normal? Thanks

Update (09/22/2015)

found out the home button is not original. is it ok to restore? or will I get error 53? thanks"