One of my control units failed during the warranty period, so I contacted https://www.beurer-schweiz.ch in Reiden. They cannot supply control units alone, I received a completely new UB90 and was able to dispose of the defective one. The Beurer DE website states that if the overheating protection is triggered, the heating blanket can no longer be started and must be sent in for a reset - they obviously do not offer this service in Switzerland. There is also a warning that if the overheating protection has been triggered, no other control unit may be connected, otherwise it will also block.