Now you know how to get the player into RockUsb mode you still have a good chance to get your player back.
Have you tried this firmware from the omega v88?
This is a Teclast c260 copy like your player.
http://www.mympxplayer.org/firmware-...lst-df739.html
Don't worry about killing the memory, you can't use it anyway, right?.
You just need to try only firmwares from players that look like yours and that have touch controls.
If you have to open the player get the pcb number and the number from the display there may be a firmware you can use on
http://www.s1fw.com/ your player uses only firmwares for rockchip RK2608A with touch controls.