why would tapping the brakes get my instrument panel working after it had all gone dead?

Hello, it's possible that something in the electrical impulse of the brake light switch could be related to a harness that is causing a concern with the instrument panel. Or, it's possible that movement of some kind in that area is causing something loose to reconnect. Either way, it's all a guess and needs hands on evaluation by a professional technician near you. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops