My intention was to say that it either probably wasn't a red light, or they were descending at idle thrust and the gear warning lights were on (totally normal). Sorry if it wasn't clear.
And yes, occasionally the door is opened to check if the bus drivers haven't died in the meantime if the head honcho in the back feels like looking at them instead of phoning them. I doubt he seriously meant the door was left wide open for minutes. Normal stuff.
Occasionally there are hassles with the pressurisation that don't get diagnosed/fixed straight away if it's some weird fault that is difficult to trace. Then the engineers start swapping bits out to try and localise the problem, but occasionally they guess wrong the first couple of times, and/or spares aren't forthcoming. Sounds like one of those times.