The switch at the top of the emerg brake often gets out of adjustment if you allow the pedal to slam into it when releasing the emerg brake.
I very seldom use an emerg brake in Florida (no hills) but when I find one engaged I place my foot on it, release the lever, and allow the pedal to return slowly by lifting my foot.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician