The tri-wing needed to open your remote is also available in iFixit's driver kits.
All the screwdriver bits you need to repair electronics, smartphones, tablets, computers, and game consoles in one handy toolkit. Kit includes Pentalobe, Flathead, Phillips, JIS (Japanese Industrial Standard), Torx, Torx Security, Hex, Square (or Robertso — 50+ available at 24.95 each.
Ultra-portable screwdriver kit for repairing electronics, smartphones, tablets, computers, and game consoles. Contains: 4 mm Driver Handle 60 mm Driver Extension Metal Tweezers Flathead sizes 1.5, 2, 2.5, 3 mm Phillips sizes #000, #00, #0, #1, #2 Torx siz — 50+ available at 19.95 each.
You can try just unscrewing the case and removing the front cover and see if that helps. The front cover is just a filter that only passes infrared light (and keeps dust out). But if you damaged the sensor inside, then you'll need a new Wii remote. To unscrew the case, I believe you need a tri-wing screwdriver, which you can get at Ebay. If the sensor is damaged, you can sell the remote to a hacker who only needs it for the accelerometer.