There was some resistance. The Nazi's actually specifically set up a resistance movement called Werewolf in 1944 when it was likely that Germany would be invaded and occupied. But this resistance was minor as you mention. The US in 1946 put out a memo listing the security threats by importance German resistance was below sit-ins by freed slave laborers who didn't want to be returned to Soviet controlled countries.

The western allies crossed into Germany in late February 1945 The Soviets in early March. Germany surrendered in Early May so wartime resistance would have only been 2 months.

The dynamics of the war also affected resistance. Nearly all German troops attempted to surrender to the US or UK. Germany killed nearly 20 million Soviets during the war. The Soviets wanted vengeance. If a resistance group killed a Soviet soldier in Soviet territory they could expect the Soviets to give a disproportionate response. You killed 10 men I'll kill every German man within 20 miles.

On the other hand. Making trouble for the US or UK would only open the possibility of the Soviets gaining ground.

Finally, Germany was tired of fighting. They had lost 10 million men most of their cities were in ruins and they had been forced to confront the horror of what they had done in the holocaust. Most Germans didn't have the will to fight on after the war.

In some literal sense, there was no one left to resist. The backbone of any armed resistance is males between the ages of 16 and 40. In Germany, most of the men in that age range were already in military service of some kind by the time the war ended. They were either taken prisoner by the Allies or dead by late 1945. There was literally no one to lead or man the resistence. Of the nearly 18 million men aged 16-45 who served in the German military (Heer, SS, Luftwaffe, etc) between 1939 and 1945, over 5.3 million were either MIA or KIA by the end of the war. Another 3 million were casualties severe enough that they didn't re-enter combat after being wounded. The rest got captured by either the Western Allies or the Soviets, and got to spend a few months cooling their heels in POW camps, if they weren't killed by natives (Italy, France, Yugoslavia) or shipped off to Gulag camps in Siberia (most the Eastern Front).

To put this in perspective, imagine and your 9 closest buddies as Christian German males between 15 and 40 in 1939. By 1945, of the ten of you, 3 are dead or missing, two are crippled for life, and maybe of you is a gibbering mess from PTSD. Additionally, of the five of you still (theoretically in) fighting shape, you've all been fighting a brutal war for the past five years, your families, if they still are alive, are literally starving, and the house you left behind is probably a pile of rubble, if you are from one of the major cities, or possibly behind enemy lines if you were originally from east of the Oder. This analysis ignores the non-combatant civilians who died in great numbers as well and are now largely homeless and starving, especially in the largest cities. By the way, your great and charismatic leader is dead.

Does fighting back still seem like a winning move?

EDIT: Sources!

http://www.feldgrau.com/stats.html

Eisenhower and the German POWs (1992) by Steven Ambrose. -- this book discusses the literally millions of POWs that the Allied Occupation Authorities had to try to feed and house shortly after the war ended, a logistical challenge as difficult as fighting the war itself.