Replaced factory radio one week ago with

Audi (VW) is NOT giving out the security codes (chat, phone) anymore. You would need to take the car to the dealer (I figure 1/2 hour to 1 hour labor, or $50-$100?).

Last week, I tried a commercial online service (paid with credit card to have a recourse in case it won't work/scam).

Submitted the serial number of the radio, entered the VIN of the car, and answered where I obtained the radio from (here: ebay). Received confirmation email, and a day later received the code. Entered the code. Worked.

The service I used (I just googled; there may be others):
(mayb VW only?):
http://vwcodes.org/

Similar (but I did NOT use them yet):
https://www.radio-code.com/Audi-Pay-Page-radio-code.htm

Phone the dealer - they should supply you with the radio code free of charge. If not - and you can't find the radio code in any documentation, consider buying a code from Ebay.

It's quite easy to enter a radio code. Here's a link to show you how to do it:

how to enter radio code vw beetle Google Search

Look at things that drain a battery such as a door not completely closed, cabin light on, radio remaining 'on' etc. Also the igntion key removed at off position versus at a notch before. Nothing else TMK drains the battery.

possible that the mechanic who sis not auto electrical qualified has damaged the alternator when fitting it of has fitted the wrong unit ( internal voltage regulation as opposed to external voltage regulation) take it to an accredited auto electrician for a bench test , have the voltage regulator tested and load test the battery as well
batteries can be defective for manufacture

Did you find a solution? If not reconnect the power wire to either ignition or accessory, this way when the key is taken out there will be no power at the radio

IMPORTANT NOTE: You must have the security anti-theft code for yours VW radio from the car manufacturer! For VW radio the sequence of programming is:
1. Push simultaneous "SCAN" and "RDS" keys until on the screen will appear "1000" displayed.
2. Release keys. No more push on "SCAN" and "RDS" keys because otherwise number "1000" will be considered as first safe code attempt.
3. By the #1 key you will set up the first safe code digit.
4. By the #2 key you will set up the second safe code digit.
5. By the #3 key you will set up the third safe code digit.
6. By the #4 key you will set up the four-th safe code digit.
7. Then push again simultaneous "SCAN" and "RDS" keys for confirm this safe code. On the screen will be displayed "SAFE" notice. Release keys! For few seconds a radio frequence will be displayed. The radio is now ready for use!

Please rate my response. Thanks!

RESET RADIO CODE, INSTRUCTION MOST LIKELY FOUND IN THE RADIO MANUAL

bad cell in your battery

both regulators have gone bad you will need new ones

I think I remember running into this once before and found a factory rear speaker amplifier in trunk that stayed powered on then we replaced the amp and the new one did the same thing . then checked radio coding and it wasn't set to proper code so it didn't know to turn off the amp. changed the coding to correct setting and bingo problem solved. hope that might help but coding can only be done by dealership.