Try those suggestions above, brake light switch and fluid level (topped up to max).
I had same issue previously, as soon as I touch the brake pedal, the lights came up. Unfortunately for me, it was an issue with my ABS actuator unit which needs replacing.
If you still have issue after checking, you might want to get ur car checked with a proper code reader. Bluetooth code reader only gives you engine codes, not electronic codes. Report back and fellow forum members can help.