When you say "restart" you mean a hard reset yes? Power off at the back? I'd say it's worth either updating the firmware (if you're not on v1.2.12) or overwriting with the same version if you are. If you're not on the current version you can use OTA to update (Settings/About/Version > "Online Update" and make sure beta box is ticked) otherwise you'll need to use a local file to overwrite: Latest firmware: https://music.eversolo.com/dmp/ota/DMP_A6/v1.2.12/DMP-A6_R_v1.2.12_202310171825_ota-package.zip Do not unzip, load from Settings/About/Version and choose "USB Update"
Try overwriting the firmware - this can only be a software error and I haven't seen it and no-one else has reported it as far as I'm aware.
If it happens after a couple of days: 1. is it on constantly? (overheat?) 2. do you reckon playing a particular track in all occasions? (could be messing it up) 3. have you used other player software? (it could somehow mess the loopback device used for displaying the VUs)