The adapter you have does not connect the pins correctly as per the TV requirements.
You can verify this yourself by checking the adapter link for the connections it makes, and the TV manual for the connections required.
TV manual explicitly says a crossover cable is needed.
The gender adapters in general never change the wiring and do not provide a ...
The shown commands should turn the TV on and off, if I read the manual correctly.
As the other answer suggests, also make sure that TxD/RxD are not swapped (pins 2 and 3 on the DE-9 pinout).