move the "ON/OFF" switch to the right (so you cant turn it on), plug it to your PC and hold the upper power button, wait until you will be asked to install the "ROCKUSB" drivers that can be found in the CD that came with your player or on the fallowing link:
http://www.teclasters.com/attachment...0&d=1189544149
in the same CD there is an upgrade software that you need to install, also can be found here:
ftp://d:d@59.39.59.99:2121/teclast/mp3/Update.rar
after all the setups are done, click on the upgrade software, open the correct firmware and click upgrade.
You can tell if your C260 is "CI" if it's written on the lower back of the player (next to the TECLAST logo and site), that's in case you have an original Teclast player. if not, it's probably a bad idea to try this.
More info about spotting the CI can be found in the word document that comes with the RAR file of the firmware.