The real reason my laptop was shutting down was that it was overheating. The reason it was overheating was that over the last year or so a massive dust bunny had been growing inside it and was blocking the fan. To remove the dust bunny, you only need a small philips screwdriver. Take out the battery, then remove the largest plate on the back. Then unscrew the fan and lift it out (don’t break the attached wire). You’ll see the bunny. Get it. Put the whole thing back together. That’s it.
Get the SG_AS5610/TM4200 service manual for the exact steps. Project took 10 minutes and saved me a repair fee and over a week of down time.