The property was in a great location; however, we experienced a concerning safety issue that was not remedied in a timely manner, forcing us to vacate. Two nights into the stay, we were awakened early morning by a fire/CO2 detector. We researched model number trying to troubleshoot thinking it was a low battery, but the beeps were both sporadic and rapid leading us to believe there was a CO2 hazard. A couple of guys in our group mentioned experiencing dull headaches and there was a noticeable, pungent gaseous smell that got stronger certain times of day which everyone noticed at check-in. I messaged the property owner immediately after trying to troubleshoot alarm; it was 6-7 hours before I received a response. By that point, we had already vacated the property for the remainder of the stay due to frightening safety issues and booked a different property last minute at a much higher rate rather than remain displaced. After the property owner replied, I advised we had vacated the property due to safety concerns/delayed response. I asked for consideration of a partial refund due to issue and followed up again 2 days later with no response. Approximately 10 days later, I received a response likely due to me disputing with credit card company. The property owner offered 250 refund which I stated was not acceptable. In addition, furniture was broke down, stair carpet/windows dirty, water damaged flooring/bathroom cabinets, and food order 3-4 weeks old at front door.