They did not generally have better weapons
The myth of German advanced weaponry comes from few excellent weapons at the end of the war, but in reality German often came to battle with inferior weapons. Overall most of the best technical weapons were allies.
Computers, developed by the West, nothing like in in Germany gave allies a massive intelligence lead
British Radar defence at start of war
Western propeller plane design was far better from the start through the war. Also allies had better bombers and attack planes.
T-34, Russians for the most part had better tanks a more of them.
German logistic was also dependent on horses as the allies had American made trucks.
Their best weapons were developed in a reactionary mode
The iconic high tech weapons of Nazi Germany, the V-1 and V-2, the jet, the Tiger tanks and assault riffle were developed after established German weapons proved to be insufficient once the applies in Stalingrad and North Africa had learned the methods of Blitzkrieg.
Weapons development was chaotic
Germans were developing dozens of new weapons, via different funding bodies and often dependent on Hitlers whim. Thus unlike the allies a wide range of sometimes strange expensive weapons were being presented rather than a few excellent version pushed through and produced in massive numbers.
If Germany had concentrated on the jet fighter, the Panther tank, the assault riffle and panzerfaust it could have made a difference in the war, but a wide range of revenge weapons were produced to no strategic benefit.
They were outnumbered
Stalin said that Quantity has a Quality all its own. One German tank commander said it took 11 Sherman tanks to take out a Tiger, and they always had 11 Sherman tanks. The British had a sub-machine gun that cost less than £3 to produce which they flooded partisans with.
Their leadership was chaotic
Germany had no effective political structure beyond just Hitler's whim. Planning and programs had to deal with pleasing Hitler who ran the country kind of like his own start up. Start-ups can create innovative new ideas, but they also have a massive failure rate.
They were so evil they turned people against them
In the end the people's of Europe cold not put up with the Germans and were happy to welcome not just the Americans but the Russians as well.
This was really a massive failure. Given how much better life was in Nazi Germany than in Stalin Russia for non-Jews who could support Hitler, one would think the German's could have easily won a war of liberation in Russia. The Soviet Union was full of nationalities that hated Stalins rule and a massive class of best and brights along with peasants in the Russian West had suffered under Stalin and it is hard to see how Hitler managed to fuck it up.
But his racial hatreds were so blinding her turned people, who normally would have been fine with Nazi rule in to violent enemies. While a Russian or American solider could count on local support and secures logistics, but the end of the war a German outside of Germany could not ever feel safe.