If I had to guess based on the prior statistic, I would say that most likely cause is the static electricity damaging V5 electronic components, like @ToshBoss and @Xenon27 had suggested. If you search the forum for ports esd or ports static, there will be plenty of hits.
If your robot has specific configuration with electrically isolated subsystem(s) that could easily accumulate electric charge and the fields in your area are not regularly treated with an anti-static spray, that could explain two damaged V5 brains in a row.
Except for the ESD vulnerability causing blown ports and WSODs and an unfortunate placement of the thermal sensor inside V5 motors, I don’t think we ever heard of any other systemic problems with V5 hardware before. It seems pretty robust if you protect it from the static during the winter months.
I agree with @jpearman that it is next to impossible to damage hardware with the ordinary code on V5. Built-in default PID values for the motors had been chosen conservatively and had not been exposed to the public. Also, eFuse chips protect each port and battery from over-current.
Your code doesn’t look like you are overriding built-in PID values for the motors or intentionally trying to run them in the worst possible thermal regime.
And for those curious about the topic of software damaging hardware beyond vex, lots of interesting reading can be found here: malware physical damage - Google Search