You may not need to take it apart. Just try cleaning up the battery bar an its connectors with some baking soda paste (little water) and a cotton swab. Here's a quick guide for the Go but should be same for touch controllers.
OK, so I cleaned up the battery leak with damp q-tips and paper towel yesterday. It was a fresh leak, it had not dried, it was easy to get the battery compartment cleaned out. BUT I SUSPECTED BATTERY LEAK WENT FURTHER INTO THE DEVICE. I made an attempt to open the device and clean it but I had no idea how. I later found out there were 2 screws under the battery label, but they are really small torx screws and I have no drivers small enough to fit them. Anyhow... I was able to play 2 hours or so of half life Alyx early today. I took a long break and tried to resume a few hours after. The left controller no longer works. The white LED flashes when I put a battery in, but that is all. I even tried the battery from the right controller, which still works. NADA. The headset says the left controller can not be found. Even after powering down and rebooting.
The battery that went in mine were energizer with best before date of 2028. LEAKY ALKALINE BATTERIES CAN DESTROY YOUR ELECTRONICS. I would recommend removing alkaline batteries after play time and never to leave them in any device!
Ya, and don't use cheap batteries as well. Many so-called Alkaline are junk. Better to use good rechargeable ones like Eneloop AA 1900mahr imho. These actually last longer than most alkaline and can be recharged many times (~500-1000) over. Plus they do not leak, lol!