Thermal paste replacement, Macbook Pro 2015

Recently I replaced the thermal paste in my Macbook Pro 2015. Doing it was straightforward -- I used this guide to know which screws to take out -- but I thought I'd record the symptoms here in case anyone else has a similar problem.

The symptoms were: the laptop would boot or almost boot, but would hang -- display would be alive, but nothing else -- and would usually then turn off within a few seconds (I guess due to some hardware watchdog?) This happened both during normal boot and safe boot. The laptop would stay alive forever if it were just sitting on the pre-boot login screen (and thus, presumably, not taxing the CPU).

In retrospect this was pretty clearly a thermal problem, but everything is clearer in retrospect. :)

In the era of glued-together phones and no user-serviceable parts, it seems anachronistic to fix a laptop with £1 of thermal paste.