Audi Concert Radio / Cassette Help checking / finding code

[Delta925]

I have a Concert unit in my A4 registered in 2000.
The unit is working but I don't have the code and need to fit a new battery.
I have got the serial number off the unit if anybody can find the number from that.

Also if I press and hold station button 3, which has 'code' above it in red, then switch on the display shows
a four digit number then a dot and M1....
' ****. M1 '
Is **** the code?
Maybe a kind person with a working unit who knows their code can check this out

Many thanks.

[wallis1007]

Buy a power supply that plugs into your'e fag lighter. You can get them for a few quid. plug it in, swap batteries, job done no need for a code!