My wireless entry failed recently due to the siren wiring short circuiting and thus I am no longer able to use my remote to unlock or lock the doors.
Not too much of a problem as I'd always wanted to replace the system as the range of the old one was quite limited.
I had bought a keyless entry system from Aliexpress since 2 years ago and had no good reason to install it until a week ago when it rained so heavily that it shorted my siren +12V wire to ground and rendered the old keyless entry system useless.
This was the system that was purchased and the instruction manual looks like this.
Honestly, even for an electrical engineer, the instructions were quite useless...
Then I found help,at Peachparts forums, where many classic Mercedes owners, contribute technically to helping other owners, in this thread.