I have a imx6solo design in production. A few boards have an issue with HDMI_VPH (ball M7). The boards run properly initial tests but fails in the next steps of production. Under failure +2V5 rail is tied to GND due to short-circuit into M7 ball of imx6solo. If I remove power from M7 ball, the +2V5 rail is up again and board runs properly, except HDMI because HDMI_VPH is internally short-circuited to GND and not powered.
Something happens in the board that lead to M7 to be GND shorted.
I have HDMI_VPH, NVCC_LVDS2P5, NVCC_MIPI, NVCC_RGMII and NVCC_ENET connected to an external regulator. Datasheet and documentation connect HDMI_VPH, NVCC_LVDS2P5, NVCC_MIPI to VDDHIGH_CAP. It could be the problem?