Corrupted Save

[Posho]

Hi everyone, sorry if I'm posting in the wrong place, I'm new here.

So, I played Pokémon Legends Z-A on a hacked switch, back when I first started the game 4 days ago, I used PKHeX to add the mystery gift rewards since I cannot obviously claim them.  Used JKSV to get the files out and into the switch, everything went fine.

Now, I just started the DLC and thought about adding the Kalos starters' megastones, so I did the same as the previous time, but now the game doesn't even load, the switch says "The program has closed due to an error". I tried to un-edit the changes I had done, but it still says the same when I try to open it.

Is there anything I can try to make it work again or did I just lost my playthrough?

P.s. When using PKHeX, I did a backup of the main save, not the backup file, maybe that's why it's not working anymore?