I fixed it at our Beosystem/Beomaster 4500. The touch glass is mounted in frames with foam.
Repair: See the instruction on the Beomaster bottom for dismantling the glass panel.
Get sticker glue remover/cleaner, remove the glass from the frames and glue the frames to the glass with very small layer/amounts of car windshield glue/kit (black kit), not the short hardening glue/kit. Do it at ease, take your time. Stunning system at the wall !!
Regards, Robert