DIAGNOSIS Water and canister vacuums don't mix. You likely got the bag and pre-motor filter wet, which immediately clogs the airflow and can trigger the motor protection. Water inside the motor is a serious hazard.
FIX Unplug it immediately. Do not turn it back on. Open the bag compartment and remove the wet bag. Then remove the pre-motor foam filter and the exhaust HEPA filter. Let everything air dry completely for at least 48-72 hours in a warm, dry place. This includes the canister interior with the lid open. Do not use heat sources to speed this up.
IF THAT DIDN'T WORK If the motor got wet, you might have a more serious problem. After everything is bone dry, reassemble with all new, dry filters and a new bag. Plug it in briefly and try turning it on. If it makes a grinding noise, smells like ozone, or trips a circuit breaker, the motor is likely damaged and needs professional service.
HEADS UP These are not wet/dry vacs. Even a small amount of moisture can ruin the motor and void the warranty. For future spills, use a dedicated wet vac or towels.