wooders

Hi, Have a problem with my ML 270, the handbrake warning light will not go out, and cannot get the car out of park. Also on the dash are the three amber lights on the left of the display are on permanantly.
A mechanic friend told me how to disengage the lock for the gear shift, and I got the car home, but now the handbrake light and buzzer are sounding.

Any ideas? my guy thinks it could be the brake switch, but we don't have the diagnostic module.

Thanks

Kevin