[lloeki]

> It's (speculated to be) flexing PCBs under BGA chips again.

Also, operational heat (from SoC, battery, whatevs...) can repetitively flex boards ever so slightly as it heats up and cools down, and on the long term will cause BGA chips to lose contact over time. That's what famously happened on the Xbox 360, but it more silently happened on numerous other devices too.

BGA is a necessity nowadays due to pin density, but it's a tech that's incredibly easy to ruin at the slightest design or manufacturing mistake.