I've tried posting this question also on the Cisco forum, with no success.
I had 2 (now 4) Aironet 1250 (AIR-RM1252A-E-K9). I tried booting them up but without success. All of them behave exactly the same: I tried a standard 802.3af PoE switch, then a C3550-24PWR switch, and then the AIR-PWRINJ4 injector without success. Even removing one or both radio, I never saw the front led come up blinking nor any output in the console (other than the ÿ character).
I played with console speed, parity, flow control, stop bit - nothing.
So, I'm stuck, I'm out of ideas; do anybody have any hint to share?