"I want him to learn how to read because it will allow him to do more
of the things he wants to do: learn about science and do science
experiments, play games on the computer that have instructions that
you have to read, read books that he is interested in."

Man somehow survived for millions of years and made great progress
without books or reading. Much science is learned by touching,
feeling, exploring, finding things out on accident, etc...that is what
makes science fun. Look at George Washington Carver. He didn't know
how to read or write as a child but his curiousity had him doing
experiments with nature long before he stepped foot into a school.

Are you not willing to do science experiments with him? Have you
inadvertantly made him think that having fun with science is only
something that can happen as a reward for learning to read? Why can't
you read him the instructions? Perhaps an older sibling would enjoy
doing some fun experiments.

We made a chocolate volcano with no directions required, it was my
son's idea. What about you making some oobleck and letting him have
fun, or baking cookies or things like that? We had more fun with our
own volcano made up with thoughts and criticical thinking of how that
chocolate would ooze out of the top, than the baking soda/vinegar
volcano or prepackaged electric volcano.