Perhaps your having just flashed it is a red herring (in that the “real” problem just surfaced right after you did such). In the vein of an “easy fix” try:
- A different USB cable. There have been reports of one or two bad cables. But when doing so be aware of the issue that some third party cables don’t quite fit right due to the recessing of the USB connection port. A cable with a large “head” may not push all the way in. See this thread for some detail.
- Take a look at this post about Misaligned USB Ports