Upstairs guest bathroom toilet had guts previously replaced incorrectly. Customer had problem with toilet running non stop that ran up their water bill. Inspected toilet and found both the flapper and fill valve were improperly installed. Received approval to rebuild toilet. Replaced flapper, fill valve, toilet handle, and the supply line. Tested multiple times to ensure proper function. Water pressure tested in normal range. Customer had the tankless installed recently. Left quote to flush the water heater. No further issue at this time.