It will be the bulb behind the heater that'll have gone they're are twistlick T5 bulbs. You can access the back if the unit via the panel underneath and above cup holder. The panel needs to be pulled out towards you
Dont forget the two torque screws behind the radio. They hold it In place as well. I tried changing one of them bulbs once just by removing the under panel but u have to know what to grab and also it is well awkward.
Take the panel below the heater off yes, nothing else.
You need to remove the metal cage.
There are metal tabs that will needs to be bent back, these help hold the cage in.
Take the cage out, two torxs screws will show theme self after. Take the out, push the heater pannel back and then take it out
I've changed the bulbs without taking the heater panel out. Just a bit fiddly.