If it cannot hold dirt, the appliance will not suck up more dirt, and in some cases the machine will actually begin to shoot out dust from its foot. The bag may not even look full, but if the change bag indicator light is light up, you need to change the dirt bag. Change the bag, and try to use the machine again.
The vacuum has several filters that remove small dirt and mold particles from the air. They also help filter out materials from the bag. If the filters get full, the machine will not pick up dirt and debris. Clean the filters before trying to use the vacuum again.
The BOSS will not suck up dirt if the appliance is on the wrong setting. For example, the carpet setting is higher than the hard floor setting. If you adjust it to the carpet setting, the vacuum can't pick dirt off a hard floor. Fix this by adjusting the vacuum setting for the correct flooring.
If the hose is clogged, the vacuum won't pick up dirt and debris. Clogs are often clumps of dust bunnies or hair. Use a flashlight to peer into the hoses, and remove any clogs you see with a long-handled brush or pipe cleaner.
If the brush roll is not turning, the BOSS cannot suck up dirt and debris, which happens when the brush roll gets covered in hair and strings that prevent it from turning freely. Fix this by clipping hair and strings from the brush roll periodically. The brush roll belt might also be broken and will prevent it from moving. Replace it with a new belt if this is the case.