I need to replace a burnt motor on my 6S build and this is my first time desoldering from a 4-in-1 ESC. Locate the problem motor(s) and desolder the three wires attached to the electronic speed controller (ESC) after removing the heat-shrink tubing. Remove the four screws on the bottom of the motor affixing the motor to the arm of the drone so the motor can be removed. What's the safest temperature setting and technique to avoid damaging the ESC pads? I have a TS100 iron and some flux. Also, when resoldering the new motor, Ensure there are no shorts (undesired connections) between any of the wires and make sure everything is properly insulated when you're finished. If any of these wires short to each other or the carbon fiber frame, it could brick your ESC.

Set your TS100 to around 350?C and use plenty of flux. Heat the pad and wire simultaneously, then gently pull the wire away with tweezers. Don't rush it - overheating the ESC is way worse than taking an extra 10 seconds per joint.

I'm still learning soldering myself, but I found that adding a bit of fresh solder to the joint first helps the old solder flow better when desoldering. Is that the right approach for motor wires too?

If you are splicing the new motor wires to pre-existing ESC wires, then slide new heat shrink tubing onto each of the three wires before soldering the new motor wires in place. If you are soldering your new motor wires directly to the pads of the ESC, you don't need to use any heat shrink tubing. Now, solder the new motor wires to the ESC or the previous wires. Always test motor direction before final assembly!