Here in Itay (I'm Italian) I can't seem to be able to have the FM transmitter work because of the very full radio stations. What do you mean about 'I do a modification to transmit FM to my car without usb connected'? Didn't it do it already? Please, could you check wether your infrared module worked? Mine didn't.
The better module seems to be a similar case, with a a different chipset (it should be a rockchip one).
Let's try and find out the more we can about this damn player
Ciao,
Fabio