Several times I will turn the key on and no power. I disconnect the negative battery terminal for a few seconds and then I can start the vehicle. The negative battery terminal has quick disconnect for when I am towing behind my Motorhome.
I would make sure the battery cables and battery post are clean. make sure the cables are tight on the posts. and you might want to put on a new quick disconnect to rule out that being the problem.
+1
Next you need to start with a DVOM or at least a basic test light to see if you have voltage at the other end of the battery cable and a good ground at the cable ends also…
But if all you are doing is cycling the quick disconnect to make it start/get power, then you might have some corroded contact points within the quick disconnect itself as mentioned above…