He soiled his pants, then went underground.
Lucky for him ( and others around him ) he had a changing of clothes.
He was very calm about it. In the closing days of WWII he was very detached and spent time looking at a table-top model of the world capitol he planned to build in Siberia. The Europeans had installed the new telephone system centered in Paris which was seized intact. Some of the front-line commanders telephoned frantically stating the continent was being invaded. Many commanders, who had been paying for gasoline out-of-pocket for the army went back to sleep. Many had moved in to estate mansions and slept with one or more German shepherd dogs. They held the Stutka dive bombers back for the defense of Berlin. The Yunkers Stuka's nickname was the 'Panzer of the air', which means 'flying tank'. Some historians consider this a fatal error. Hitler started getting nervous after the Battle of the Bulge.
Hitler refused to believe the D-Day invasion at Normandy was the REAL invasion. Due to some expertly accomplished subterfuge, the allies successfully concealed that Normandy WAS the landing site. If Hitler had thrown ALL of the German forces at Normandy, it is doubtful the invasion would have succeeded.
According to one source I read, he SLEPT. He was extremely fatigued and left strict orders that he not be disturbed. Because there were also strict orders not to move many powerful German units without Hitler's express permission, they had no choice but to sit there as their fellow soldiers near the coast were overrun. We were extremely fortunate that the Germans failed to fully mobilize in response to D-Day.
how did Adolf Hitler react to d day?