My experience with burnout is exactly like you described FYI. It was like my mind just couldn’t process properly. I couldn’t read, or engage in thought on anything with any depth or acumen. Coupled with the burnout was a depression and deep anxiety. If you meditate a lot then I’d suggest examining with your awareness what is happening when you’re reading. If you’ve coupled some Buddhism with your practice then you can examine whether you are resisting / reacting. With burn out it happens at a subconscious level, but you should be able to sense a resistance when trying to engage in things you have trouble with. Do you feel joy? Interest in things? Can you remember what music you like? These sorts of things are useful to ask yourself.

Finally, I assume you’re male. Have you had your testosterone levels checked?