My Zedboard does not properly power up, power OK LED does not light up, but all the user LED's light up red. I debugged the problem that IC27 (Vadj generator) has no voltage at its output. Before the problem occurred, J18 was set to have 3.3V at Vadj. There was an Inverium FMC mezzanine card (TB-FMCL-PH) attached to the FMC connector, and there was a custom made ADC board connected to the PMOD B connector of Zedboard. In the attached photo you can see the whole experimental setup. In the photo, "Digilent" corresponds to Digilent Analog Discovery 2, "level shifter IC" on the breadboard (in the middle) and the receiver IC in the converter (right of the photo) are HEF4104B. The problem occurred after I used single ended digital inputs of Analog Discovery 2 to see the LVCMOS 3V3 outputs of Zedboard on the FMC mezzanine card.
As I understand from other posts in this forum and some others, either the IC27 or the whole Zedboard should be replaced. But before doing that, I need to understand the problem that lead to burn IC27 not to repeat it again. Can you please help me to find out?