Zero failed to boot with serial port connected to a device

If I connected the serial port with my device through GPIO pin 8 and 10 (UART_AO_A_TXD, UART_AO_A_RXD), the Radxa Zero with Debian 10 failed to boot.
If I removed my device from the serial port, zero can boot.

After booting, I connected my device to the UART port, it worked well through /dev/ttyAML0.

Any suggestions? Many thanks!

That sounds really odd. Make sure you connect the ground wire as well but not the VCC wire.

I bypassed the u-boot serial console to fix this problem. Thanks!

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Hi ycai,
I have the same problem, could you specify how you bypassed the u-boot console?
Thanks!

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Hello, Could you comment on how you solved it? is that I have the same problem.

Thanks…!!!

Did you fix it?

Thanks