2005 audi a4 wont start after changing the battery

SOURCE: 200 AUDI A4 WILL NOT START AFTER BATTERY CHANGE

make sure you have the correct battery for you car.

SOURCE: Audi A4 1.8 1996 do not start

Have you tested the battery for power drain. If not, this should be your first step to a solution. If there is any aftermarket audio equipment, radars, gps, etc. One may be pulling enough current to drain the battery. If you know how to test for this sort of thing great, if not take it to any local car audio store, car toys, best buy, circuit city, even auto zone and have them test for current drain. This is a time staking process. The negative terminal of the battery must be detached and in line with your multimeter. You must then wait for all of the cars computers, lights, etc. to turn off. If there is current drain, you should be able to go through the vehicle and unplug any aftermarket equipment one by one to see which is the source....also pulling fuses may help as well. (keep in mind that during testing, if any door is open, hood light switched on, you will not get an accurate reading.) I highly reccomend consulting with a professional.

SOURCE: 2005 Audi 1.8 a4 check engine light on and car now spudders??

FYI also when you get those codes you can look them up and get their description at http://www.check-engine-light.com

SOURCE: Audi A4 tail lights come on at night and drain my battery

its the sensor in the brake pedal, happens mostly at cold nights since cold weather loosens up the pedal it causes the pedal to go down by itself if like you were braking, I used to roll up the matt and put it underneath the pedal and that would put pressure upwards while i was researching on how to do it myself found out is complicated and decided to take it to the mechanic for a 200$ fix.

SOURCE: 2005 Audi A4 1.8 Fuel Pump problem?

I had an Audi A4, 10 years older than yours mind you, but it would start then stop, sometimes 10 times but would eventually go. I ran a little WD40 in the key barrel and put the key in and out a couple of dozen times. Wiping it with a cloth each time, lots of dirt came off. My theory and it's only mine, is that the wear on the key left dirty metal deposits inside which stopped the chip in the key being recognised. I believe they had a security chip inside the key.
Anyway after 6 months of this nuisance it never happened again after that. Fixed my problem and a lot of frustration. Maybe help you too.