My 4yr old dropped a PS4 controller it my 30 gallon tank and it was there for a minute before I could get it out. Is there any way to repair it?
Sure, it's unlikely to have been permanently affected unless it was connected to power (powered up electronics suffer corrosion due to electrolysis) and even then that's a short immersion time so the risk of permanent damage is low.
Take it apart (video yourself doing it so you can get it back together), wash it in distilled water (most importantly the circuit boards) to remove any contaminating salts which will cause enduring corrosion, leave everything to dry overnight (maybe with a fan assisted electric heater on low setting, some distance away) and reassemble it
Be aware that chips on circuit boards can trap water underneath- if you don't have any compressed air blow out gun/aerosol consider at least blowing down a drinks straw around the chip edges to dislodge any trapped water so it can evaporate away (and endeavour not to get spittle on the board)