Hold CMD+R (internet recovery)

Did my first Iphone 7 display swap today, mind that you often cant use the suction cup if the screen is cracked. Thin metal spatulas is the best. I did bought a thin strong spatula from ifixit.com several years ago, its now broken and the ones they are selling now is not strong and not thin.

Another tip is to be very careful with the home button flex, DO NOT HEAT because it make the flex more sensitive. Be also careful when peeling the front camera flex, use plastic tools.

Good advice two: When removing the LCD back shield plate have in mind that the home button connector attached to the shield plate is Very fragile. Its adhered to the screen. Use very little force and do not heat the adhesive too much because then it become even More fragile.

I use ifixits metal spudger without heat but one small mistake and it can be teared.

Its a good advice to remove the battery power before mounting the flex-cables.

There is power on the second logic-board (even if the phone is turned off) connector from top, misplacing it while assembly can cause short circuit.