Symptoms are very easy to check. Measure voltage between inductor and GND. If the voltage is lower than 9V, you can be sure PIC is not working. If the voltage is higher and less than 10.5V, PIC is malfunctioning, partially working and you need to remove it or remove U2.
Correct voltage of string: 10.5V
Partially working voltage: 9-10.5V
PIC not working voltage : less than 9V (usually 8.7V)
I concur with this assessment (for the most part).
I had a batch 16 board failure within 48 hours. Measures 9.16V - doesn't work at all - reads 30 chips.
I have another board that was an RMA replacement from batch 9 that partially works (actually seems to work best when around 69-72c) reads 10.12 at start and 10.26 at load.
Normal-fully functional board measures 10.56 at start and up to 10.69 at load.
Ordered some trimmers today, looking forward to resurrecting boards - unless bitmain RMA gets back to me first.
So on the partial working unit will i need to remove the U2 chip?