Unable to get serial console or boot linux on MCIMX8Q!XP-CPU (Si B0) - only garbage on UART

[drupadh]

Hello,

I am facing issues bringing up the MCIMX8QXP-CPU (Silicon Revision B0) board.

Hardware:

• MCIMX8QXP-CPU (Si B0)
• MCIMX8-8X-BB baseboard
• IMX-LVDS-HDMI adapter connected to J1
• Original 16 GB SD card that came with the kit
• Also tried a newly flashed 32 GB SD card with official Linux BSP (L6.18.20 / MX8QXPC0 image)

Problem:

1. Serial console (J11) always shows only garbage characters (□□□□) at 115200 8N1.
   • Tried multiple COM ports
   • Tried different terminal software (PuTTY, Docklight)
   • Tried on two different Windows laptops
   • Installed latest FTDI VCP drivers
   • Same result with original kit SD card and newly flashed card
2. UUU never detects the board in Serial Download Mode (SW2 = 1000). uuu -lsusb shows no device. Board does not appear in Device Manager when in download mode.
3. HDMI – no display output so far (using IMX-LVDS-HDMI on J1).

Boot switches tried:

• SD boot: SW2 = ON ON OFF OFF
• Serial Download: SW2 = ON OFF OFF OFF
• eMMC: SW2 = OFF ON OFF OFF

What I have already done:

• Flashed official .Sdcard image using Balena Etcher and Rufus
• Verified SD card is properly inserted in J12
• Used original power supply
• Checked multiple USB cables for the debug port

Could someone please advise:

• Is there any known issue with Si B0 boards regarding the debug UART?
• Any additional steps to get clean console output?
• Recommended way to recover / verify the board is healthy?