I brought two of those model's for my niece and nephew for x-mas. After they unpacked it and set it up, they notice some of the buttons are not working. So after contacting the seller directly over the phone they emailed me two of the firmware. it was hit and miss, one work perfectly on one phone and so was the other.
****EDIT***** sorry I can't post outside links. so, they are both uploaded to my mediafire
just add the mediafire url at the beginning and it should lead to the download. If you need the whole link for some reason just PM me.
They are both in .PAC format to be use with researchdownload. And one more thing make sure on the Calibration tab, uncheck everything or else it will fail at FDL2. The older one label the V06 has more option but just make sure nothing is checked also.
My phone model is the HTM GT-T9500-B SC6820 with the 5" screen. So try them both.