The red lever is a pure air ("Ackermann") valve. Open it and the brake pipe gets emptied immediateley. The red button is a electronic emergency. It lowers the panto, opens the MCB and opens magnetic valves to stop the train gently. If the eddy brakes are on, they get used too then.
What's the restart procedure? I hit the button (electronic) just for fun, and found that the brake pipe simply would not recharge, even after resetting the panto and MCB (The air compressor was working, topping up the MR, but the air just bled out of the BP)
You may need to pull out that red button before. It is not a bush button, it stays down and you need to pull it back.
