You cannot boot the "wetek-play2" image from SD card without first erasing emmc (use emmctool from the box image) because if vendor u-boot exists on emmc the box always boots it and not mainline u-boot from the SD card. The boot partition on the SD card contains only extlinux.conf for mainline u-boot and this is not seen/understood by vendor u-boot; hence it cannot find legacy boot files. You can of course copy s905_autoscript etc. over from the box image but this replicates booting the box image from vendor u-boot which doesn't proove the issue with mainline u-boot is resolved.
So, erase emmc to force mainline boot from SD card. If the noise issue is resolved then it should boot. If it is not resolved, it will drop to the u-boot console where you can type 'boot' to continue booting. If you want/need to revert back to vendor u-boot I have a raw disk (dd) backup that can be downloaded and copied to /storage on the SD card and written back using emmctool again.