why not change the thermostat, Its the easiest fix besides a radiator cap. Are you dripping any water while the car is running? Could also be the waterpump.
I've unplugged/plugged my cluster plenty of times with the srs light never coming on. Did you perhaps unplug the srs harness? That light is your e-brake.
Only about 3,000 miles of daily driving, so nothing too abusive. I've inspected them regularly with no tears in the boot and very minimal adjusting on the allen bolts.