If the driver stops at a platform by mistake
Bear in mind that if there's a red at the end of the platform the driver may not have much of an option! What happens if you do stop out of course at a platform can depend on the stock and the relevant rules and company policies.
When we still drove slam door stock it was pretty normal when you knew you had a red at the end of a platform to try and avoid actually stopping as there could be quite a delay if the guard was unaware of what was happening (especially so if they were in a portion of the train that wasn't on the platform).