I didn't think it was that complicated when I got mine. Tug on the tab, didn't come out. Pull a little harder, didn't come out. Pull a little harder, still not coming out. Push on the back, slides off, remove battery, remove tab, reassemble.
i7 5820K @ 4.25GHz | RTX 3080 Ti FTW3 | Gigabyte GA-X99-UD4 | Corsair DDR4 3000 32GB | Corsair HX 750W
SSDs: Intel 660p M.2 2TB, 3x Samsung Evo 1TB | Startech PCIe 4x USB 3.0 | Startech PCIe 2x USB C 3.1 gen2