Troubleshooting ROCKPro64

[alephnull]

I recently bought a 4GB ROCKPro64 (including power supply) and am unable to make it boot. I have a serial adapter (running at 1500000bps) connected and have tried the following:

• FreeBSD-13.0-ALPHA2-arm64-aarch64-ROCKPRO64-20210122-02611ef8ee9-256201.img.xz on a SD card.  This displays `U-Boot TPL 2020.10 (Jan 22 2021 - 04:33:21)`
  
• Armbian_20.11.10_Rockpro64_focal_current_5.9.14.img.xz on both SD card and eMMC.  This displays `U-Boot TPL 2020.10-armbian (Jan 05 2021 - 04:11:42)`
  
• buster-minimal-rockpro64-0.9.14-1159-arm64.img.xz on SD card.  This displays `DDR Version 1.19 20190305` then `In`
  

There is no output following the output messages listed above and the board is not responsive to serial input.  I have tried 2 different SD cards (SanDisk Ultra 16GB A1) and in all cases, verified the data written to the card against the original image file.

Based on RockPro64 boot sequence, the "U-Boot TPL" lines suggest that the TPL is loading but the lack of a subsequent "U-Boot SPL" line suggests that the subsequent SPL loader is not starting.  The ayufan boot prompts are different but I'd expect something similar to my Rock64, which starts:
DDR version 1.13 20180428
ID:0x805 Y
In
SRX
LPDDR3
786MHz

I have tried raising a support ticket but, after more than a month, that has gone nowhere - the only suggestions have been to run a memory test, without actually providing any suggestion as to where I might find a memory test that doesn't require a fully functional U-Boot.  Can anyone here suggest additional troubleshooting steps I can perform?

Hi, you eventually could try to erase the spi and flash it again (https://github.com/sigmaris/u-boot/wiki/...oot-to-SPI)

I reproduce the same behaviour when the RXD (white wire) is connected (see https://forum.pine64.org/showthread.php?tid=6387). Try to disconnect this wire and reconnect it after the boot.

Thanks for that.  I can confirm that if I disconnect the RXD until after U-Boot starts then everything works.  That's a particularly nasty bug in the boot ROM but I think I can work around it (once configured, I won't have ready access so manually connecting wires isn't possible).