This guide worked well for me but I agree with others that: -

1) A different method for disconnection the battery is needed. I broke the edge of mine doing as instructed.

2) Some explanation of the best way to fold or bend the new cable in place is needed.

This is extremely fidley. My closeup vision isn’t good so resorted to clamping my iPhone in place while using the Magnifier function with lamp on focussed on the job to enlarge what I was doing. I felt like a surgeon doing keyhole surgery :-)