What messes up the save feature on Golden Sun games?

[Douglas]

I just purchased a 'Lost Age' game off of Amazon, but when I play the game it simply starts off by letting me name the characters (no continue file to choose from), and when I try to save, it says "Unable to detect backup memory". 
I've googled this, and apparently I'm not the only one who has had this problem.  It also seems that this problem cannot be fixed.  I'm ordering another GS2 cartridge, in which the description says that the 'game holds a save and has a continue file'. 

My question is, what causes the game to not be able to save, and how can I prevent it from ever happening?  (The only thing worse than buying a GS game that won't save is buying the game, getting halfway through the gameplay, and THEN the save feature messes up.  That would be a big, big bummer.  ).

Also, I hope this was the appropriate section of this forum to post this in, as it was a 'Lost Age' cartridge I had this problem with. 

[Ailanthus]

I'm really not sure what's wrong. I think Lost Age and even Broken Seal used flash memory, so it's probably something wrong with that.
I've no idea what causes those to go bad though, I'm guessing just flaws in it's manufacturing or maybe turning off while saving and getting it corrupted a few times could do the trick.

Save files not working anymore is a more common problem with games that use watch batteries to save. They can go dead but can be replaced.
If your TLA has one though, that means it's bootlegged. That would suck but at least then you'd probably be able to figure out how to fix it.

[Shadowfyst997]

The internal battery on the cartridge is dead. It happened to my copy too. Basically, GBA games have a little memory device or something inside, and since gba games are pretty old, the ones that have had a lot of play simply cannot hold a save anymore. APPARENTLY this is something that can be fixed, because i know a game shop irl that says they will fix my copy for 15 bucks, but i haven't done it yet. I had my copy for a long time and one day it just....did that. I was quite choked as I had been playing it on and off after several complete playthroughs, and my peeps were like, level 70, which takes FOREVER to get to.