replace the fucking battery then. its easy as shit

>>26177663
I don't want to risk fucking up my game cartridge, and I don't even know how the hell to do it or where the hell to get the right type of battery.

>>26177671
Do you have an R4? You can easily create a backup of all your GBA games:
https://www.youtube.com/watch?v=LBEbgvjwC84
After that you can safely switch batteries.

>>26177739
Forgot to mention but even if you can't switch batteries you can probably use a cheating device to alter the time of day. It won't make it cycle naturally but at least you can get to the low tide part of the Shoal Cave.

>>26177671
If you have a general store (Wal-Mart, Target, Walgreens, or whatever the equivalents are if you live outside of the US), you can find it. It's just a standard type of watch battery.

>>26177671
Battery type is CR1616. Drugstores and such have plain ones for sale for like $3 or something. Tabbed ones on ebay go for like $4 with free shipping.

If you get a tabbed one then you can melt the solder on the tabs of the dead one and solder in the new one. If you don't get a tabbed one then you can pry the tabs off the dead battery with an exacto knife, then use electrical tyape to attach it to the new one. GBA games don't rely on the internal battery to maintain saves, so if the tape comes off you just gotta re-attach it.

You'll also need a tri-wing screwdriver to open the cart, those usually run for like $8 online or at a local game store.

>>26177871
>tri-wing screwdriver
This is the best way, but I'm just gonna chime in to say that I managed well enough with one of those tiny flatheads that you can find in things like eyeglass repair kits.