Nand causing Switch not to boot?

I’ve been using a v1 unpatched Switch with a payload to test if various eMMCs are good. The good ones I can read and the bad ones it will say fail to init. One eMMC will just render the switch dead. Black screen, doesn’t go into RCM mode, nothing. Has anyone else seen this behaviour? Nand chip looks fine, no shorts on any of the caps on the eMMC board. I tried a reflow but it’s still the same.