On disassemble, the unit was visually inspected for any other possible damage from liquids, foreign objects from kids, insect damage or even electrical damage that may be visible like overheated areas, burn areas, corrosion etc.

In this image, we can see the motherboard. It is in clean condition for its age and there is no sign of obvious damage.

There an edge connector which connects the cartridge to the motherboard and can simply be removed by pulling off to reveal the PCB contacts. These looked in good condition but the contacts were cleaned with isopropyl alcohol and fine steel wool. Only a very quick and light rub was done as we don't want to lose much parent material although if it is degraded severely, then a simple re-tinning of the contacts with solder will help with this.