If water level and filters are not the problem, the two rows of dashes would usually indicate a pressure switch or circuit board problem and the pressure switch would be the more likely culprit. You could try "jumping" the pressure switch to see if the dashes go away. If so, replace pressure switch, if not, then continue troubleshooting.
The dashes should not prevent you from being able to adjust the temperature on the display. When the hot tub was reading 105, what was it set for?