Vokera linea he 32 hot water problem

[Covedod]

Having problems with Linea he boiler.When running hot water boiler needs to be reset after about 5 minutes.
At first it was only lasting about 1 minute then needed rest.
I replaced hot water thermister and the problem seemed to be fixed for a few days but now it's started locking out after about 5 minutes.
The display code is showing 55 which says problems with the pcb. Just wondering if anyone had had a similar problem.

 

[Millsy 82]

You need a gas engineer. It can get expensive guessing parts and you could put yourself and your family I danger messing with your boiler

 

[Dotty]

Don't mess about with things you're not qualified to work on.