Just happened to me during my audio overhaul. He disconnected the battery, and that was that for the FRM.FRMs do fail ..on power up, change of battery and on coding…increasingly common on E90s..eg E89
Relatively cheap fix..about £50 in uk with someone who knows e90 FRMs..bench job..
Yup its an ageing and sensitive device..fortunately a relatively easy fix..till the next time..Just happened to me during my audio overhaul. He disconnected the battery, and that was that for the FRM.