Use some tape to limit how far the screen will open. I used wide packing tape, stuck it to the bottom of the display, where the home button is, and to the opposite side, on the back. It left a loop of tape, front to back, around the bottom of the phone, that had about an inch of slack. This allowed the display to pop off completely without any danger to the home button cable. No prying required.
Overall great guide. I have followed it very carefully with 100% success. Here’s some advice:
1) Do yourself a favor and get the iFixit 5s battery replacement kit. The tools are really good and help a lot.
2) via goldenimaging: Use tape to limit the amount the displayed can be opened. Zero chance of ripping the touch ID cable.
3) Apply heat even before attempting to pull the adhesive strips - the back of your phone should be hot to the touch. They become more elastic and don’t rip so easily. But still pull as slowly as humanly possible and resist the temptation to go any faster :) Re-apply heat before second strip.