If you're a beginner electronics hobbyist you know that the capacitors on most battery-operated objects aren't powerful enough to kill you but can still provide a painful jolt of electricity if not discharged before removing from a circuit board. Build a capacitor discharge tool using a resistor, two pieces of 12AWG wire or larger and heat shrink tubing.
This design comes from online repair database iFixit who uses it on their well known device teardowns. Solder the wire to each end of a resistor designed for moderate current demands (at least 2k Ω 5W and possibly more depending on what you're discharging) and add heat shrink tubing to cover the connections.
Full step-by-step instructions and photos can be found at the source link below. If you're not sure you're using a resistor or wire that's heavy duty enough for your application make sure you consult with a professional.