Sound not working on Jelboz360/Debian Trixie/kernel 6.12.6

[jbbandos]

Describe the bug
After rebooting, the sound briefly works, for 1s or less. Then it won't work anymore.

Boardname
jelboz360

Logs
debug-logs-Jelboz360-2025-01-10_18h18m.tar.gz

[jbbandos]

Clarifying, at first use less than a second of sound can be heard, then silence. Later, very loud bursts of static at random times, independently of how loud the sound is set or even muted.

./setup-audio --branch syntax-7 doesn't change anything. alsa.ucm.conf is version 1.2.13-1
speaker-test -c 2 hangs at "front left" without any sound. ctrl+c and it exits with "Interrupted system call"