Was able to clear drain via overlfow and pulled back large amounts of hair. Inspected waste and over flow via access behind tub and saw over flow was plumbed in with an improper drain and was leaking. Strongly recommend replacing of P trap and waste and over flow for bathtub. Also performed camera inspection via roof vent and found that tub drain had large amounts of build up and could not see condition of drain due to build up. While drain is open due to replacement of p trap I recommend performing descaling and following up with camera inspection to make sure there are no further issues. Replaced waste and overflow for bathtub as well as performed snaking to drain. Followed up with camera inspection and everything was draining properly. Customer had large amounts of build up inside of existing drain. Was able to remove majority of build up by snaking and descaling. Ran bathtub for several minutes and everything was draining properly