💻 Laptop Internals Upgrade Bench: Battery Runtime, NVMe Swap, Dual-Channel DDR5, Heatsink Paste and Fan Dust

Open a laptop from below and upgrade it hands-on: unplug the 86 Wh battery, strap on ESD protection, swap the M.2 SSD, add a second DDR5 SO-DIMM for dual channel, clean dusty fans and renew thermal paste at the right screw torque, then stress-test with a two-node thermal model.