get out of engineer mode and get rid of tamper?

Hi I have a honeywell galaxy 2 system, it needed a new battery the engineer talked me through that, but the panel kept saying tamper and nothing we done could get rid of tamper, he said he would come out yesterday and fix the problem, I have not heard from him since and have called him several times, the panel is saying engineer mode, I have his code to put in, can anyone help, Maggie