Dx7 grey. Won’t bind to anything

[Captain Video]

I have a grey Dx7 which won’t bind to any of my planes that my dx6e, dx6i and dx4 will. How can I troubleshoot this unit. What can I look for. I understand it is older but I have used it as buddy box but not as a flight controller as I got it broken. I have been flying for six years so I understand how it should work. Any advise would be great.
Thanks
Captain V
Westerville Ohio.

 

[DamoRC]

If it doesn't bind but works well (?) as a buddy box unit then I would assume that the controls, switches, and firmware are working as they should leading to a conclusion that its the radio transmission unit that's broken. Have you opened her up yet? Any obvious damage to the transmission board, antenna connection or cuts / breaks in the antenna wire?

DamoRC

 

[Captain Video]

Thanks for your reply
I have openned it bit the antenna is connected and there is no obvious problems
I am perplexed
Is there a good way to determine if the transmitter board is bad
Any advise would be great