Did Jesus go to heaven to apply his blood to the mercy seat there?
I believe that was His purpose on the day of His resurrection. He hinted of this in the morning while speaking to Mary Magdalene (John 20:17). By evening He was back (John 20:19). Also the writer of Hebrews made mention of Him entering the Most Holy Place of a tabernacle that’s not part of this creation with His own blood in the capacity of our High Priest (Hebrews 9:11-14). The only time a High Priest could enter the Most Holy Place was on the Day of Atonement to sprinkle the blood of the sacrifice on the mercy seat.