Answer:
inspect the CPR mask and make sure that the one-way valve is correctly in place.
Step-by-step explanation:
Based on the information provided within the question it seems that the next logical step would be to inspect the CPR mask and make sure that the one-way valve is correctly in place. This valve allows oxygen to be pushed into the victim's lungs but does not pull the oxygen back through the valves, that is part of the chest compression's that the person performing the CPR needs to do.