Troubleshooting Tips

First steps

Pretty much any issue you encounter can be explained by a missing solder joint, an unwanted solder bridge (especially between fine pitch pins), or a part that's in the wrong orientation. So spend time checking over all the parts and making sure they're in the right way (if they are polarized, there will be a pin 1 indicator on the board, usually a small triangle on the silkscreen) and check all solder joints. Even if a joint doesn't look problematic, it could have a hidden bridge or a hidden missing connection, so reflowing joints with lots of flux is usually a good idea.

My game wont hold a save

If they're on your board, check to make sure you have the switches/jumpers in the correct position to get your game the correct amount of RAM space.

Check your coin cell battery voltage - it should read 3V or higher if it's fully charged. Sometimes, off-brand coin cell batteries will arrive nearly or completely dead. This has been the case for me in the past. I recommend only buying new parts from reputable sellers to reduce headaches.

Also check the current coming out of the battery by measuring the voltage across the battery-series resistor.

The current coming out of my battery is high AND/OR the voltage on the SRAM is very low

As with the previous issue, make sure the save battery actually has a proper voltage and isn't actually dead.

Next thing is to make sure you've powered on your cartridge at least once. This can be done in a Game Boy, or in a cart programmer. The battery management IC may need to be initialized by applying main power at least once.

If this does not fix it, then go back and check to make sure everything is soldered properly and in the correct orientation, and are the proper values.