My GE front load washer not starting, all tests are good. No error code
In the GE owners manual it lists the symptoms you describe. It says the door will lock and unlock and will take 30 seconds to do a system check. If it still doesn't start open and close the door firmly; then press start.  

Edit
If this doesn't solve the problem you probably need a repairman. If it's within warranty - terrific. If not call a GE recommended professional. It may be possible that someone on this site can help you but we would need a lot of more detailed information including pictures. Even then if someone here could diagnose the issue you'd probably still have to call someone to fix it. Good luck.