My expierence wih fermented feed...

[ChickenLegs13]

When I do it I always have about an inch of FF left in the bottom of the bucket each morning after feeding. I dump in new feed, add warm water, stir it up, by the next morning it's bubbling with that beer smell. I don't add any ACV, secret herbs & spices, supplements or do voodoo over it.
If I kept it for a week it would be just plain rotten instead of fermented.

It shouldn't smell like beer. Alcohol is dangerous for chooks and is not the desired fermentation we look for in fermenting feed.

It shouldn't go rotten after one week, that indicates an imbalance somewhere.

So, Chicken Legs, does that mean you start a new batch each week? I thought it was like sourdough or kombucha, where you just add feed to the original batch every couple of days.

I add more water and feed daily with enough in the ferment bucket to last several days, so when they eat it, there is grain at all levels of fermentation.

No, it means that I start a new batch every day, using the inch or so of FF left over in the bucket from the previous day as a kicker to start it faster. I don't use the double bucket method, I just make it & serve it from the same bucket.
I don't make a batch then dip out of it all week. I make a batch in the morning and let it sit all day & night, stirring it up real good 2 or 3 times during that time, then feed it the next morning.
If I don't use the batch that day, by the next day it's bubbling & smelling more better, but the feed crumbles part has turned into liquid mush and the chickens have to drink it rather than eat it.
Feed crumbles are finely ground and start to bubble 5-6 hours after mixing it; if I add whole grains like scratch feed then it takes longer for the larger, harder grain to soften & bubble, 10-12 hours.
I live in a hot, humid, jungle like enviroment where there's plenty of spore, cultures, pollen etc blowing around and that makes mine kick off faster I guess.

Like other pointed out, I think you just aren't stirring it often enough.
Hope that helped.