The letter L appears on all plate settings and plates wont work?

In response to fairly common answer given by some responders, "go search online for the manual" to many questions posted here, this one being a prime example. I feel it is far more productive to give the full answer if possible rather than suggest people look for a link or post one that may be incorrect or not available in the future.
By avoiding this type of response, we can build a comprehensive resource of answers for future users with the same problem as the original poster. Most of the helpful replies are provided by people who really don't mind taking the time to write a full reply whether the information would have been easily available or not. I scan the unanswered posts and try to reply to those, drawing from my vast knowledge and experience of repairing many items. It seems a shame that questions with junk answers will be left unnoticed by people who could have offered proper help.

Rupert
June 2020

What Rupert said. Better still, you could search for the manual online yourself.

Phdsr
June 2020

Hi Alistair,
You've not provided a model number so my general advice is all I can offer. The 'L' symbol indicates that the safety lock is activate. There should be a padlock button on the controls, press this for a few seconds and the lock mode will be deactivated. If you don't have this padlock button, reply with the exact model number and I will guide you on unlock procedure.

Rupert
June 2020

I did a quick Internet search and found this:

https://www.fixya.com/support/t15811116-unlock_lamona_induction_hob

You must have missed it
May 2020