MacBook Pro as opened, and after a clean-out. Then the cover was put back on, and the operation checked - as before. Taking that no further. It has reaffirmed that my policy before being persuaded to take a look was correct, "no smartphones or Apple products!"

I do have tools to take it apart - and remove the back, obviously - but to attempt the supposed soldering required on it, a good binocular microscope, much finer soldering iron, other tools and numerous service aids would be required. I don't charge for repairs, and I'm not prepared to spend the amount of cash required to work on things like this, especially when a repair can't be guaranteed.

Must learn to say no, as undoubtedly mentioned before...

(Edit: extra added with the only thing that appears on the screen)