Firstly, hats off to you for trying to properly diagnose the problem and trying everything that you did. Hope you find the solution soon. Some random suggestions if you haven’t already tried - clean the battery contacts (I’m not sure of the best method to do so but I’m sure you can find something online), check to see if the problem exists in different screen refresh rates, turn off auto brightness if its on.
First, you set up a company, doesn’t matter the name. Hire the bare minimum number of employees maybe one to handle accounting, and one sales person to start. Make sure you pay them either minimum wage or slightly under, with a false promise of introducing a profit sharing mechanism soon to keep them motivated. Then, the magic starts. You handle key clients yourself and make your sales target various demographies - sell this graphic for 1 bison dollar per jpeg. The trick is to sell the first million within 3 months. Show these sales to banks or investors and ask them for a further 500 million to expand and scale up your sales. Then, you vanish to an unknown island in the Pacific. Easy money.