"It can also be argued that life can be measured in power cycles, too."
Power cycling (mostly due to thermal cycling) is the root cause of many component failures but typically the number of cycles is extremely high prior to failure however components that run at higher temperature will age more quickly due to the more extreme thermal cycling. A typical failure of this sort occurs when the connection between the primary chip substrate and the external connector pad (or pin for older non-SMD components) fails from multiple heat related expansion/contraction cycles.
But the 70D failure appears to be one or more components that are failing quickly either from self-generated heat or heat from another component and occur at what should be early in the camera life. These likely aren't from terminal/pad separation but from heat related destruction of the active devices. But only Canon knows exactly what has/is happening to cause this failure.
In cameras with a lot of age/usage that don't fail due to shutter fault are likely to die from failure of one or more electrolytic or tantalum capacitors. In most well designed electronic equipment failure from these passive components is far more likely than failure from an active device (i.e. integrated circuit). There was a rash of these types of failures starting around 15 years ago from Chinese sourced capacitors that used a electrolyte formula acquired through industrial espionage but it wasn't quite complete and this problem was well known in the computer industry although other products (large flat screen televisions in particular) were also impacted.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
