Altai OST 5m 5 tragbares/Bankoszilloskop - funktioniert nicht

Altai OST5M 5mhz Portable/Bench Oscilloscope - Not Working Bought in unknown condition but I don’t know how to service it. When plugging in no response from the on/off switch no led lighting up. Nice late 80’s model hopefully someone can repair or even good as a prop :)

eBay