K5TOOL gave this as a response to hello:
And the same for attempted reboot:
Did you tried it when radio was turned on in a usual mode? I'm asking because your screenshot shows that the radio sends bootloader beacon packet which happens when radio in bootloader mode (turn on with pressed key to get LED on).
-hello and -reboot commands should be send in a normal mode (when radio is working), it will not works in bootloader mode.
The bootloader mode is intended to upload firmware. And since your radio reports bootloader 2.00.06, it should works ok to upload firmware. This is standerd version of bootloader. If serial port is not broken of course...
It shows error, just because you're trying to send hello packet when the radio is staying in the bootloader mode.
When the radio is in bootloader mode, it supports only -wrflash and -wrflashraw commands.
In order to use -hello and other commands, you're needs to disconnect the cable, power on the radio in usual mode and then connect cable.
Before flashing new firmware, take full eeprom backup, because custom firmware may modify some calibration data. You can read eeprom backup when radio is in usual working mode (not bootloader mode when LED is on and nothing on the display).
Bootloader mode => -wrflash and -wrflashraw commands only
Normal mode => -hello, -rdee, -wree, -rdadc, and other commands, but NOT -wrflash and -wrflashraw.