Volvo A40 BM

I'm looking at a used Volvo A40 2000 year model I believe and the battery voltage light is on and the stop light is flashing on the dash is these correlated with each other? The voltage at alternator and the batteries is 27 volts. So what sets the stop light off? The digital display up by the head liner don't work would that tell me what the problem is?

Volvo A40 BM