You can find the service manual @ elektrotanya. Waizt until "processing" disappears and "download" appears.
https://elektrotanya.com/sony_cdp-557esd_707esd_sm.pdf/download.html
I assume the voltage circuit for D/A conversion is seperated from the rest, Maybe it is dead (but the enlighted
optical lout hints that there is power)
About voltage: 90% of the circuits run on voltage regulators, so for a short time, an overload shoulkd do no harm.
BUT: In old players the filaments for the display get the voltage directly from the transformer. They could get blown...