My audi won't start up so I found out the battery was bad and I just put a brand new battery in it and it ran for 3 days and now its doing the same thing again what else could it be?

NEW RELAY MIGHT FIX IT

Does it roll over? If not your starter solenoid or starter may be bad.

are the inside of the battery terms dirty,corroided? do you know if motor alt is charging batt? how long did it run when you put new batt in? if it lasted about two days, its proubly not charging, also make sure nothing is being left on draining batt down, to check that, leave batt nuhooked pos side over night.

Either its a bad new battery or tour altenator isn't charging it. Jumpstart it.

You would have checked the charging system before replacing the alternator, so I will assume the charging system is good.
If the battery is being discharged overnight or over a few days, you would need to disconnect it and check every circuit on the truck to find the drain.

It is just imposs to diagnose this without wring diagrams, you will need them and we do not have them.

Fuel pump driver module is bad .
F150 Expedition No Start P1233 Fuel Pump Driver Module

I'm guessing you checked the fuses already, so if you have spark at the plugs, look for a vacuum leak. If you still suspect the fuel pump, do a fuel pressure test.

I think you have a bad fuseable link. Also,
I suspect your alternator is not charging your battery.

You have power with the new one, and it ran for the 20 minutes on your old battery. There also may be a
starter relay unit under the hood.

starter wont click because there's not enough "juice" to turn it over. this isnt because of the battery as you have just replaced it. it is due to a bad alternator recharging the battery as you drive. if it were only a fuse it would be the solenoid in the starter. but if it had started after you installed the battery then its not the solenoid. solution: buy a refurbished alternator and