Airbag light

Replaced airbag ecu last year and started my car yesturday and their was a loud bang in the front seating area. Instantly the airbag service light illuminated. I thought maybe the airbag ecu had bliwn again but didnt make a loud bang last tume. Done the reset thingy on the dash several times it stays off when I furst start it. But once enjine is off and started again comes back on and goes off again about half hour after whilst driving. Also have checjed the wires conecters seem ok. And sunroof started leakin under the frame have taken the frame out and resealed and sealed the glass also but still have a pool in the foot well. Any ideas or am I better off buying a new car which is not a french connection