Also have a 28CDi, it’s a piece of piss to remove the casing which is NOT gas sealed. FWIW I’m pretty sure the board is behind the lower panel so you don’t even need to take the top case off. There is a service manual that shows how to open it up if you don’t have one already.
For all those advocating not servicing I hope you have deep pockets when it inevitably eats itself. I got mine done last year for the first time since 2019 and the condensate catch tank was choked with gritty crap that had made its way into the flue, any longer and it would have properly blocked and caused damage.
That’s before you consider the fact that the seals and combustion gets checked on a service. Purely from a safety point not servicing is nuts. Yes, I know I didn’t and feel pretty stupid in hindsight.
