A cordless drill offers you portability without the hassle of staying near a power outlet or lugging around an extension cord. The device may malfunction during use, or fail to turn on; you might notice an unusual burning odour or strange noise. When this happens, assuming the device is no longer under warranty, you may find it cheaper to figure out the problem and repair it yourself. Otherwise, purchase a new drill.
Consult the cordless drill's manual for a "Troubleshooting" section. Many manuals will list a series of common problems encountered with that specific cordless drill and suggest possible causes and solutions. Scan through the list for symptoms that most closely match your drill's problem, then look under the corresponding "Solution" section for steps to repair the problem.
Analyse the outside of the cordless drill carefully for any obvious problems, such as a crack in the plastic, bent metal parts, or rust streaks near the air vents. A crack in the casing may have loosened an internal mechanism that you need to repair, for example. Rust near the air vents could indicate water damage and a rusted motor or wire connections. A bent component may prevent the drill from functioning correctly.
Remove the battery. Some cordless drills have a single button on the battery, while others have a button on both sides. Press the button(s), then either slide the battery horizontally or pull downwards, depending on your drill's design. Set the battery on the charger to ensure that it is charged when you need it.
Open the cordless drill if you can identify no obvious problem from the outside. Insert an appropriately sized screwdriver into the screw slots on your drill and turn the screws counter-clockwise. Use a magnet to remove the screws after you unscrewed them if they won't shake loose. Set the screws aside in a cup or plastic bag. Lift the plastic side of the drill carefully and set it aside.
Sniff the inside of the drill. If it smells like burnt plastic or rubber, the drill may have overheated, received too much electricity or caught on fire. It may not be repairable.
Check each wire on the circuit board for a loose connection.
Insert a drillbit into the drill and turn it by hand while watching the motor. The motor may be damaged if it sticks, turns unevenly or makes a grating noise.
Shake the drill gently and listen for rattling parts, which could indicate a broken switch or damaged motor.
Purchase a replacement part for the component that went bad. Remove the bad component and install the new part in its place. For example, purchase a new circuit board if the original circuit board is cracked or damaged. Purchase a new motor if the old motor rusted. Consult with the drill's repair manual for specific instructions on replacing the specific component that went bad.
Solder any loose wires back to the circuit board by holding solder to a hot soldering iron over the wire until a bead of solder adheres to the wire. Touch the wire to its connection on the circuit board, then touch the bead of solder with the soldering iron to connect the wire to the board.
Call the manufacturer and describe your cordless drill's symptoms. They may be able to identify the problem or offer possible solutions.
Wear soldering gloves when soldering wires; hot solder can cause severe burns to unprotected flesh. Attempting to repair a drill that is still under warranty may void the warranty.