Please take a moment to tell your story with a bad R4 and lets push them to take care of this mess!
I recently purchased a R4B1, work stable but it's very temperature sensitive.
If boards are cold ( below 20 degrees C ), they won't be detected.
Once it run and produce heat, all good.
But a Cold start it didn't like it.
Window of operation look very thin.
My S7-LN's have no problem at same temps.