I tried yesterday. I created all 256 commands for device 0.48, but none of these is a discrete power on command. Command 0 is toggle on/off command and it's corresponding to the toggle on/off learned. Unfortunately there is no other command that turn the device on.
I don't know if I should try with other device numbers.

A little note on the last bytes of the code: 35 91 35 97
it's in every learned code I have (for this humax) and something very simlar is even in the codes generated by Makehex, so I don't think it's a "garbled version of the NEC1 repeating frame". Anyway I don't have any idea of what it is.

Thank you for the advice for parsing bytes in the right way.

It definitely represents the NEC1 repeating frame. It looks to me like an incorrect representation of that. But I'm not certain it is incorrect. (I am certain of what it represents).

The "something very similar" may be a correct representation of the NEC1 repeating frame.