You need to check the 230v voltage on the Alde PCB to see if it is receiving the 230v. I had a similar issue panel worked no 230v icon.
Checked on the Alde PCB for 230v, the board was only receiving 9vAC, checked on the Sargent box all good. Followed the power cable to a push connector under the front drawers, took the coffin box off and found the neutral pin was pushed out, re spread the tangs and pushed the pin back into its housing, reconnected the two halves of the plugs and 230v now on the boiler PCB, all working fine now.
The picture with the switch in, I would replace that one, I am guessing your heater is a 2kw as those switched spurs are only rated at 10amp!!