Stop using it immediately. A grinding noise indicates internal damage or binding of moving parts. Continuing use risks complete tool failure or personal injury.
Disconnect the battery pack. Check for an obvious cause: ensure no accessory (bit, socket) is damaged and is properly installed. Remove the accessory and inspect the chuck and anvil for visible damage or debris.
If that didn't work, the tool requires service. Do not disassemble it. Have your power tool serviced by a qualified repair person using only identical replacement parts. This maintains the tool's safety. Using a damaged tool is dangerous.
Heads up: Regular maintenance prevents this. Check for misalignment, binding of parts, or breakage before use. Many accidents are caused by poorly maintained tools.