after not using it for a few months, my v20 drill won't turn on even with a battery i know is good, totally dead.

Diagnosis

The total loss of power in a Craftsman V20 CMCD700C1 after prolonged storage is typically caused by one of two things: surface oxidation on the battery contact rails or a "locked" electronic controller. When these drills sit in a humid or non-climate-controlled environment, a microscopic layer of non-conductive oxidation (often appearing as a dull film or white powdery residue) forms on the copper-plated terminals of both the battery and the drill's internal connector. This creates enough resistance to prevent the trigger switch from completing the circuit, even if the battery is fully charged. Furthermore, the CMCD700C1 utilizes a digital control board that manages the brushless motor and torque settings. If the battery was left partially discharged or if there was a static discharge during storage, the internal protection circuit can enter a "sleep" or "fault" state. In this state, the logic board refuses to send power to the motor to protect the cells from deep discharge, effectively bricking the tool until the residual energy in the capacitors is drained and the circuit is reset.

How to Fix It

To resolve a logic lock or surface oxidation issue, follow this specific sequence to clear the capacitors and restore electrical conductivity:

1. Remove the V20 battery pack entirely from the tool.
2. Squeeze and hold the trigger fully depressed for 60 seconds. Do not release it. This drains the remaining voltage from the internal capacitors on the control board, forcing a hard reset of the electronic switch.
3. Inspect the battery terminals. Use a cotton swab dipped in 91% isopropyl alcohol to vigorously scrub the gold-plated contact pads on the battery.
4. Inspect the female terminals inside the drill's battery port. Use a dry toothbrush or a compressed air canister to remove any dust, lint, or debris that may have settled in the slots during storage.
5. If you see visible oxidation (dullness), use a precision needle file or a small piece of fine-grit sandpaper (400 grit or higher) to lightly scratch the contact surfaces of the battery. Do not gouge the metal; you only want to remove the oxide layer.
6. Slide the battery back into the port, ensuring you hear a distinct "click" from the locking mechanism. Apply firm pressure to ensure the terminals are fully seated.
7. Slowly pull the trigger to test for power.

If That Didn't Work

• Test with a different V20 battery pack. Even if you believe your current battery is good, the internal cells can develop a "surface charge" that shows full voltage on a multimeter but collapses instantly under the load of the drill's motor. Try a battery that has been actively used in another V20 tool recently.
• Check the torque collar alignment. On the CMCD700C1, if the clutch ring is stuck between settings or jammed due to debris, the internal safety switch may prevent the motor from engaging. Rotate the torque collar through all settings (1 through 20) several times to ensure it is clicking properly into place.
• Inspect the trigger switch for physical failure. If the tool was stored in a way that put pressure on the trigger, the internal spring may have collapsed. If the trigger feels "mushy" or does not snap back instantly, the switch assembly may need to be replaced.
• Check the battery's internal fuse. If the battery was stored in extreme cold or heat, the internal protection circuit (PCB) inside the battery pack may have tripped. Place the battery on the V20 charger; if the charger light flashes red immediately or does not light up at all, the battery pack itself has failed internally and is not delivering power to the tool.

Heads Up

• Avoid storing V20 batteries at 0% or 100% charge for long periods; 50-70% is the ideal storage level to prevent cell degradation.
• Never use WD-40 or oil-based lubricants on battery terminals, as these attract dust and create an insulating layer that causes the exact power failure described above.
• Store your tools in a climate-controlled environment. High humidity accelerates the oxidation of the copper contacts in the CMCD700C1.
• Always remove the battery before performing any maintenance or changing drill bits if you are working in a high-vibration environment to prevent accidental trigger engagement.