OK, let's see if I can help, but first you have to help us help you.
When you say you flashed something, please give us more details. I.E., what exactly is the name of the file you tried to flash. Also and more importantly, did you try the steps that guidot asked you to try; mainly the part about using RSD Lite 4.6. In my experience with using RSD Lite, the version can make a big difference as when RSD lite gets updated, the updates work fine for the newer phones, but don't always work for the older phones.
Let us know, thanks.