Just a tip for older consoles - replacing the battery cells

[Ciaran]

This applies to any cartridges that have on-cart saving capability or consoles that have a Real-Time clock battery cell.
These typically last between 10-20 years, most will take a CR2032 battery cell in consoles and a CR 2025 or CR2016 in the cartridge - you can check which yours take.

If you need breakdown guides, iFixit offer guides and TronicsFix also has lots of repair videos, some including how to replace the power cell.
For some instances you will need access to a soldering kit and security-bit screwdrivers. You can buy these on amazon or iFixit have some sets you can purchase aswell.
Some tips out there involve swapping out the spot-welded battery clips with a battery holder instead for easy-replacing in the future but you'll need to ensure you have enough clearence to close the cartridge completely.

Battery cell replacement is particularly important for the older Playstations(PS3 especially) and you most likely need to redo the firmware.