This drawing shows you how to build a programming cable for your Hytera repeater.
I hope it helps.
Regards
If you don't have access to a DB26 connector, you can use a DB15 connector and then cut off the right side of the shield so it can be connected to the back of your device.
As shown in the following drawing.
I did it this way because it was difficult to find a DB26 connector.
Regards.
To put it into firmware mode!
While the repeater is off...
Attach and use an SM16A1 microphone (the one that comes with the MD786 or similar)
Attach the microphone holder so that this action closes the ground circuit.
Press and hold the PTT button.
Connect or turn on the repeater.
Make sure the notification LED turns red and the repeater will be ready to receive the update.
All of this according to the service manual.
Regards