You already checked all connections from ESC to FC to PC and installed the newest version of the FETtec Configurator?
The blue LEDs on the ESC are blinking?
Please follow these instructions:
1. Connect ESC to FC to PC without lipo and press connect in FETtec Configurator
2. "no ESCs found"
3. now connect a lipo to ESC and press connect again
4. all ESCs should be found now