Exactly the same problem - disconnected battery to replace light / indicator unit. Only the first number of code was accepted i.e displayed on radio. Two weeks later steering angle sensor was reset using fiatecuscan. Radio code NOW accepted first time. But steering angle sensor faulty, and replaced, then calibrated using fiatecuscan again. But back to the problem of only the first number of the code being accepted.
Have tried the following unsuccessfully:
(a) disconnect battery for 15 mins / disconnect for 1 hour / disconnect batter for greater than an hour
(b) left ignition on for 1 hour
(c) drove car for 1 hour!
No WAIT message. CODE present reappears after 20 seconds.
I'm thinking about taking the Blaupunkt out and reconnecting in the hope of resetting the radio... Can't think of anything else.