We could talk about radiation for a long time, and I'm not an expert, so I'll just bring up a few points.
Our LEO satellites in equatorial orbits are *not* in a harsh radiation environment. Satellites that traverse the van Allen belts, or are in a polar orbit, are.
What makes a semiconductor "rad hard" or not? The main problem is that radiation can cause unwanted conductivity across a semiconductor junction. And rather than an *intended *junction, it's often between some IC detail and the *substrate.* And once conduction starts, it may require removal of power to stop it *if you're lucky. *If you aren't lucky, overcurrent blows that detail off of the IC.
So, for radiation hardness, ICs are fabricated upon an insulating substrate, rather than a semiconducting one.
This was the origin of the silicon on sapphire chips, which were incredibly expensive. These days silicon on insulator is used, and can be just as expensive because they may be fabricated in small runs without economies of scale.
However, some chips are already fabricated on insulator as part of their regular process. A number of modern CPU/gate-array combinations are, and are available at decent prices.
Once one eliminates the substrate issues, there is still the issue of radiation across intended junctions. This is in general handled by various sorts of redundancy, and sometimes the ability to power-down the IC.
Historically, AMSAT used a silicon-on-sapphire 1802 CPU which was not booted from a ROM. It was booted by a hardware modem from a ground upload. So, this could not be "bricked" as long as the hardware was intact and working. The OS would continually scrub the memory pages with a read-correct-write cycle.
Modern CPUs are more complicated and often less reliable. There was once even a project to fly a cell phone! Giving these things a simpler bootstrap processor, which could take over if they failed, might be a good idea.
And if your satellite can't recover if launched with a dead battery, IMO you asked for the problem.