Help please! MK3 NC heater stuck on Full Heat

[Roadster_Robbie]

Could be a MOSFET…

Mx5 NC fan speed stuck after fan replacement

My model of MX-5 is: nc1 I’m based near: Bristol I’m looking for technical help or recommendations on: how to repair fan speed setting. So I recently replaced my 2006’s blower fan with a newer 2011 used one and all was well and good until one day I noticed that the fan was stuck at a mid-high setting. Trying to change the speed did nothing and for a while I couldn’t switch the ac on or off either (same button). Does anyone have advice on what this might be?