I have a 4 year old 7975 phone that is not under a Cisco support contract. When the phone is plugged in to either poe or ac power adapter the only thing that happens is the speaker light will turn on and stay on. When I try the factory reset by holding the # key down, it does not respond to this, the speaker light just turns on and stays on.
I have also tried powering it up with the headset removed. The headset, mute and speaker lights turn on first, then just the headset light is lit, then just the mute light and then then the speaker light. Once again the speaker light stays on.
I called Cisco and that is a dead end as it is out of warranty. Just wondering if there is anything else I can try before I pitch it?