I owned a bunch of these over the past year and half, MyRig was able to successfully repair all of them that lost boards plus I did not have to ship the entire rig.
Currently trying to get a hashboard repaired there now but customer service is not replying promptly. Their customer service is hit or miss, must be all the smog in Denver

Good to know, just reached out to them on a couple boards I've had go bad.
I too think it's a shame the R4 isn't produced anymore. It's a great device for people who have access to inexpensive power in places where noise would be an issue. But I get that there's unlikely to be bulk buyers.