@elliottbnewcombjr thanks so much for that! Some specs there I hadn't found yet too. Super helpful. If I'm feeling even braver, and brash about going well out of my depth, I'll definitely revisit these tips. I got an assortment of metric screws and found some M3s that work perfect for securing the cover. Found an actual power button (well-hidden on the bottom of the unit and oddly neither indicated nor mentioned in the user manual). Connected the RCAs, speaker cables, and power and crossed my fingers. Alas, didn't power on. Definitely looking like I'm gonna have to bring it in to a professional and hope it's salvageable.

