Any clues for restoring a brittle, wooden crate?

Clean it off and sand it to stop the splintering.

Are the broken boards mendable? You can sister some thin wood strips or use decoratI've metal strips to fix those. Are some sections of board missing? Maybe you can patch the holes with some macrame or tin. Add elements to make it an artistic container or package box for your front porch. It can hold reading material for in the bathroom. It can become an umbrella holder by the front door or even a hanging shelf!

: )

Is there enough wood left to restore? Or will you be adding more wood than is there already? Are there bugs? Mold? Rot?

Is there something about this particular crate that makes it valuable to you?

You might want to rethink this project before you put time and money into it.

Probably not the kind of answer you were looking for - I have started many projects that had to be abandoned because I had bitten off more than I could chew.

From the description alone I would say repurpose it as firewood. I am sorry that I couldn't give you another answer, but without a picture to show me the shape it is in, I wouldn't know what to recommend for restoration and repurposing the crate.

I would suggest you soak it in mineral oil, as much as it will take. Takes time, but might be worth it, even if you only get a board or two salvaged. Mineral oil doesn't go rancid so is the best choice.

If you decide to use the wood after cleaning, sanding, debugging, and trimming it, I suggest you use a backing and flooring. You can find wood pallets for free wood that may not be in as bad a shape as what you found previously. 😇