I had those same faults (specifically handbrake and "ECU NOT PRESENT") When my ATC CONTROL UNIT took a swim due to leaky rubber glands in the boot lid (trunk lid). The fault was intermittent until the unit finally bombed. I was fortunate enough to have had a mechanic allow me access to his parts bin and to shorten a long story, swapping out the unit solved my problem... No need to have it coded to my vehicle either which was a relief. Not saying that's your issue here but perhaps you could add it to your check list. It's located in the boot right next to the battery.

Sent from my GT-I9500 using Tapatalk