If one is smart, one brings it to a shop to have it changed.
If one isn't, one opens the case, buys a temperature-controlled soldering station (half-decent ones start at about $100), unsolders the old battery, solders in the new battery, and one hopes that he didn't overheat the battery or slip in some way, damaging some component that's going to take a $200 trip to the repair shop to fix. (You pay by the hour for them to figure out what you broke. Then you pay for the repair. Which is why some good shops won't even take a job like that - they know that they're going to end up with a broken tab or phone because you're not going to pay more for the repair than a new one costs, but you're already into them for the time it took to find the problem, so they have a lien on your tab - IOW, they own it.)
If it involves opening a phone or tab, it's usually a lot cheaper to pay to have it done.