I have a TYT TH9000 that I’ve been using without any issues for about 2 years. Two days ago, I powered up the unit, listened to some traffic on a local repeater, turned the channel knob to a different channel, and the display immediately read “kill”. I have no idea how to get the unit back to operating. I’ve read everything I can find, and see no mention of this problem. I have never programmed any DTMF tones, or any other tones into the unit other than PL tones for repeaters. Anyone have any ideas? TIA