Has work been done to repair the boiler control board?

Question

Electronic components

Hello.

Not strong in radio electronics, so I ask for help.

At my house today, the craftsmen "repaired" the Junkers gas boiler.
From the very beginning, I was diligently convinced that it was necessary to repair the electronic control board of the boiler and that they often broke.
I was told that the board burned out as a result of overvoltage.
Due to a certain behavior, I immediately suspected the uncleanliness of the repairmen.
Therefore, when the board was brought from repair, I carefully examined it.

It turned out that the board is pristine, that is, there are no traces of soldering in principle.
As if the board is only from the factory.

Tell me, do I understand correctly that it is simply impossible to repair an electronic board without visible traces of soldering?

Thanks in advance for your answers.