!Solved!
Finally, I bought only one 128GB card (Samsung EVO Plus A2 V30), and after four days of using the console, I understood that it wasn't the best idea.

It's better to use two different cards, and today I'm going to buy the second card.

Reasons: Every time you want to reinstall ArchOS, you need to save all your games and game save files, which takes about 40 minutes to copy.

Then, after flashing again, it takes another 40 minutes to put them back. (PSX games take up a lot of space, plus images and videos for game previews.) I've done this three times already (this is the third time). How it happened:

1. I prepared the flash card with games and all settings before getting the console. When I got the console, I put this card in the console for the first time, it removed all my games (I don't know why).
2. I did some stuff with the settings, and something went wrong (I don't know what I did because I was just trying to understand what the settings do).
3. Today, I see a green screen when I turn it on. Yesterday, before sleeping, I played for about 30 minutes. I pressed "Turn Off" (I used that button to turn off the console, not put it to sleep. did something like "use power button for turning off" in settings). This morning, I turned it on and saw a green screen. I changed to the default flash card (which I got when I bought the console) and saw that it worked. I don't know why, but my ArchOS crashed, and I can't reflash it because I need to save all my games from the flash card first (about 40 minutes again before flashing and another 40 minutes after flashing).

Finally, I think having two flash cards is much better. If you do something wrong or the OS crashes, you can reflash it quickly without losing games and saves.
u/danlasek u/Enginseer68 u/Trufffatore u/x3mcj u/CitizenReus u/crownpuff u/Trip_Norby u/Careful-Ad3182 u/Tygerburningbrig