Hi man, i know im a couple month too late but i had a similar issue and as an electrician myself i did some test, i took entry voltage =good, output zero...
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Then at first i took the multimeter to check if the big Transformer were getting the voltage but nada...
Then after a last look bit on despair side ... i've seen that familiar rubber cylindar near the plug and of course the protection fuse had busted and after cutting the rubber carefuly , you could see easy.I just cut near board very carefuly the wire which was quite tick and done a descent size soldering operation with a wire jumping from the plug wire to the board itself.
Worked like a charm and been pushing the asic to the limit and so far nothing went wrong.(that machine went with vibration stuck near the installation wall and fan got blocked but always be carefull, protection fuse dont blow for no reason and if you bypass it and you dont know why it has busted, next time its a scrap psu and even fire risk .Best will be to go the the electronic store get a remplacement and there is cheap fuse holder .
Well always look at the fuse protection at first even if it quite hidden in M3X under that thick rubber, because 2200W psu remplacement are expensive for this old whatsminer.
I hope it help or if you already know all that , your a boss man
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(im french so dont hate me for my grammar lol)
Peace