Electric parking brake dead? [T27]

Zühülf! Wouldn’t have thought to post here so quickly because of a defect … Sister just on the way with the Avensis (T27) when suddenly the warning check parking braking system is displayed. Apparently, the brake was automatically solved at the start. Just checked the responsible fuse in the engine compartment and that is ok, cables look good so far. Manual operation of the parking brake switch does not result in any feedback. chem on/off the engine, short drive and a new attempt. If, despite the warning signal, you continue driving, you quickly get an annoying acoustic warning … Means: the parking brake can no longer be pulled. Question(s): What can be the problem and is there the trick17 or must a workshop be consulted (possible costs?)? Thank you very much!