A blast from the past, an old BBC micro with an exploded X2 capacitor in the power supply.
This type capacitor is used in many different power supplies and is usually placed across the live and neutral.
After many years or decades they can explode, giving off a pungent smell.
It was requested that all the power supply electrolytics be replaced along with the two X2 capacitors.
As the X2 capacitors (the PSU had two of them) and some of the electrolytic capacitors have very high voltages across them the new parts were sourced from a reputable component supplier (not eBay or Ali express) to ensure they were the real deal.
Capacitors replaced and the broken solder joints on the three LEDs by the keyboard repaired the BBC micro was given a quick test, not that I could remember how to make it do anything!