2004 Saturn Ion

while driving all my instrument gauges stop working, the power door locks click and the seat belt warning bell sounds and there is a service message about the power steering. (power steering is fine) when i apply my brakes everything resumes working. and then, the process repeats itself. i’ve been to local saturn experts and they don’t have a clue. my mechanic says it needs a new car computer but when they tried to replace it, they weren’t able to program the new one. when they put the old computer back together the car was fine, for awhile. now, it’s starting all over again. other suggestions i’ve been given is to try a new battery, or that there is a bad relay switch. any ideas? thanks!